1) Protons, neutrons, and electrons have different charges and masses. Protons have a charge of +1, neutrons have no charge, and electrons have a charge of -1 but their mass is almost zero.
2) Static electricity occurs when electrons are transferred between objects through friction, leaving one object positively charged and one negatively charged. Opposite charges attract and like charges repel.
3) Lightning is caused by a buildup of static electricity in clouds. Static electricity can be dangerous if it creates sparks near flammable gases or materials. Earthing removes excess static charge to prevent sparking.
1) The document covers various topics in physics including distance-time graphs, velocity, acceleration, weight, forces, work, energy, electricity, atomic structure, radiation, and the universe.
2) Key concepts explained include the relationship between force, mass, and acceleration, calculating work and power, types of radiation and their properties, and the life cycle of stars ending in red giants, supernovae, neutron stars or black holes.
3) Safety issues around electricity, radiation, and nuclear processes are addressed.
Radiation can cause damage to cells and DNA which may lead to cancer or genetic mutations. The main dangers of ionising radiation are killing healthy cells, stimulating cancer growth, and causing mutations to DNA that can be passed down generations. Radiation exposure is measured in dosage, and dosimeters are used to monitor the dose received by individuals. Protective measures include increasing distance from sources of radiation, limiting exposure time, and using shielding such as lead to absorb radiation.
This document provides an overview of key physics concepts covered in Unit 2, including:
1) Velocity, acceleration, and graphs related to distance and time.
2) Forces such as friction and weight, and concepts like terminal velocity.
3) Energy, work, and transformations between different types of energy.
4) Static electricity, circuits, and electrical safety concepts.
5) Radioactive decay and atomic structure.
The document discusses the history of ideas about the solar system and how telescopes have helped increase understanding. It describes how the geocentric model of Ptolemy was replaced by the heliocentric model of Copernicus, though the Church did not accept Copernicus' idea initially. Galileo later used a telescope to provide evidence supporting Copernicus. As telescopes improved, more planets were discovered. The document also discusses how refracting and reflecting telescopes work to magnify distant objects in space.
EM radiation comes in a spectrum from radio waves to gamma rays. All types transfer energy in packets called photons. The higher the frequency, the more energy each photon carries. EM radiation can be transmitted, reflected, or absorbed. Ionizing radiation like X-rays and gamma rays can damage DNA through ionization. Non-ionizing radiation like microwaves only heat tissues. The carbon cycle and greenhouse effect influence Earth's climate and temperature. Global warming is likely caused by increased carbon dioxide from human activities. EM radiation is used to transmit both analogue and digital signals for communication technologies.
P1.5 Presentation.
Useful for revision for exams as it contains accurate information.
It includes:
- What are Waves
- Waves Definitions
- Energy Transfer
- Wave Speed
- Frequency & Time Period
- Light & Sound
- Reflection
- Refraction
- Diffraction
- Measuring Waves
- Oscilloscopes
- Ray Diagrams
- Using Light
- Red Shift
- The Big Bang Theory
This final presentation completes the whole of Physics (P1). This'll hopefully become part of a bigger collection of other science topics, soon to be uploaded.
Thank You. To all of you out there who may find my presentation helpful in any way, shape or form.I pleased to now be able to say the P1 Collection is now complete. Soon I'll be uploading other presentation on Physics, such as; P2 & P3 Hope you find these presentations useful and helpful for exams or just general revision. More presentation coming soon on this channel, JaskiratK.
See You Soon,
Jaskirat
Created By: JaskiratK
Uploaded By: JaskiratK
Information By: BBC Bitesize
Pictures/Images/Diagram: Google, BBC Bitesize
Slideshare: http://www.slideshare.net/JaskiratK
Prezi: https://prezi.com/user/mrnfvgaamzxe/
1. The document discusses electromagnetic radiation and its various uses including communication technologies like radio, TV, and WiFi.
2. It explains how different types of electromagnetic radiation such as infrared, microwaves, and radio waves are used to transmit information over long distances.
3. The document also covers topics like how digital signals make communication more robust than analog by sending information as discrete pulses rather than continuous waves.
This document provides an overview of physics concepts related to electricity and nuclear physics. It discusses electrostatics, including charging insulators and generating electric sparks. It also covers uses of electrostatics like in photocopiers and defibrillators. The document discusses nuclear fission in power plants and the challenges of nuclear waste disposal. Safety topics like circuit components and radiation treatment are also summarized.
1) The document covers various topics in physics including distance-time graphs, velocity, acceleration, weight, forces, work, energy, electricity, atomic structure, radiation, and the universe.
2) Key concepts explained include the relationship between force, mass, and acceleration, calculating work and power, types of radiation and their properties, and the life cycle of stars ending in red giants, supernovae, neutron stars or black holes.
3) Safety issues around electricity, radiation, and nuclear processes are addressed.
Radiation can cause damage to cells and DNA which may lead to cancer or genetic mutations. The main dangers of ionising radiation are killing healthy cells, stimulating cancer growth, and causing mutations to DNA that can be passed down generations. Radiation exposure is measured in dosage, and dosimeters are used to monitor the dose received by individuals. Protective measures include increasing distance from sources of radiation, limiting exposure time, and using shielding such as lead to absorb radiation.
This document provides an overview of key physics concepts covered in Unit 2, including:
1) Velocity, acceleration, and graphs related to distance and time.
2) Forces such as friction and weight, and concepts like terminal velocity.
3) Energy, work, and transformations between different types of energy.
4) Static electricity, circuits, and electrical safety concepts.
5) Radioactive decay and atomic structure.
The document discusses the history of ideas about the solar system and how telescopes have helped increase understanding. It describes how the geocentric model of Ptolemy was replaced by the heliocentric model of Copernicus, though the Church did not accept Copernicus' idea initially. Galileo later used a telescope to provide evidence supporting Copernicus. As telescopes improved, more planets were discovered. The document also discusses how refracting and reflecting telescopes work to magnify distant objects in space.
EM radiation comes in a spectrum from radio waves to gamma rays. All types transfer energy in packets called photons. The higher the frequency, the more energy each photon carries. EM radiation can be transmitted, reflected, or absorbed. Ionizing radiation like X-rays and gamma rays can damage DNA through ionization. Non-ionizing radiation like microwaves only heat tissues. The carbon cycle and greenhouse effect influence Earth's climate and temperature. Global warming is likely caused by increased carbon dioxide from human activities. EM radiation is used to transmit both analogue and digital signals for communication technologies.
P1.5 Presentation.
Useful for revision for exams as it contains accurate information.
It includes:
- What are Waves
- Waves Definitions
- Energy Transfer
- Wave Speed
- Frequency & Time Period
- Light & Sound
- Reflection
- Refraction
- Diffraction
- Measuring Waves
- Oscilloscopes
- Ray Diagrams
- Using Light
- Red Shift
- The Big Bang Theory
This final presentation completes the whole of Physics (P1). This'll hopefully become part of a bigger collection of other science topics, soon to be uploaded.
Thank You. To all of you out there who may find my presentation helpful in any way, shape or form.I pleased to now be able to say the P1 Collection is now complete. Soon I'll be uploading other presentation on Physics, such as; P2 & P3 Hope you find these presentations useful and helpful for exams or just general revision. More presentation coming soon on this channel, JaskiratK.
See You Soon,
Jaskirat
Created By: JaskiratK
Uploaded By: JaskiratK
Information By: BBC Bitesize
Pictures/Images/Diagram: Google, BBC Bitesize
Slideshare: http://www.slideshare.net/JaskiratK
Prezi: https://prezi.com/user/mrnfvgaamzxe/
1. The document discusses electromagnetic radiation and its various uses including communication technologies like radio, TV, and WiFi.
2. It explains how different types of electromagnetic radiation such as infrared, microwaves, and radio waves are used to transmit information over long distances.
3. The document also covers topics like how digital signals make communication more robust than analog by sending information as discrete pulses rather than continuous waves.
This document provides an overview of physics concepts related to electricity and nuclear physics. It discusses electrostatics, including charging insulators and generating electric sparks. It also covers uses of electrostatics like in photocopiers and defibrillators. The document discusses nuclear fission in power plants and the challenges of nuclear waste disposal. Safety topics like circuit components and radiation treatment are also summarized.
The document discusses photocells and how they work to convert sunlight directly into electrical energy by using silicon crystals. When light energy is absorbed by the silicon, electrons are knocked loose, creating an electric current. The power output increases with greater surface area or light intensity. Photocells have advantages like being renewable and producing no pollution or needing fuel, but cannot generate power at night or in bad weather. Solar panels and passive solar heating are also discussed as methods of collecting solar energy and converting it to heat.
A vacuum flask reduces the rate of energy transfer through its design which uses an insulating vacuum between two walls. This prevents convection and conduction from occurring which would otherwise allow the liquid inside to lose heat to its surroundings more quickly.
1) The document discusses various topics relating to physics, including temperature, thermal energy, heat transfer, waves, electromagnetic radiation, communication signals, and ultraviolet radiation.
2) It provides explanations, formulas, and examples for concepts like specific heat capacity, latent heat, reflection, refraction, diffraction, total internal reflection, and analog vs. digital signals.
3) The document also covers applications of these physics principles including fiber optics, lasers, cooking with microwaves and infrared, receiving phone and wireless signals, earthquakes, and the ozone layer.
This a gathering of notes collected from many resources put together to present the content of the AQA GCSE core science physics Unit chapter 5. I made it to help me revise, I jus uploaded it so others can take advantage.
The document provides information on various topics relating to energy transfer and physics, including:
- The three main methods of energy transfer by heating are conduction, convection and radiation.
- Infrared radiation is emitted by all objects and the hotter an object is, the more infrared it emits. Dark, matte surfaces are good absorbers and emitters of infrared.
- Particles have more kinetic energy when they are at higher temperatures, allowing processes like conduction, convection, evaporation and condensation to occur.
- The document also discusses generating electricity, electrical energy, waves, the electromagnetic spectrum, and provides evidence supporting the Big Bang theory of the origin and expansion of the universe.
This document discusses various topics related to physics including:
1) Different types of telescopes like optical, radio, and x-ray telescopes and how they observe different parts of space.
2) The life cycle of stars and how stars like our sun are formed and evolve over time.
3) Red shift phenomenon which provides evidence that the universe is expanding as galaxies move further away from us.
4) Different types of waves like infrasound, ultrasound, seismic waves and how they are used to detect volcanoes, do pre-natal scans, and examine the inner structure of the Earth.
Ultrasound uses high frequency sound waves to create images of the inside of the body. It works by sending sound waves into the body which bounce off organs and tissues and are detected by the ultrasound machine. The time it takes for the echo to return and the speed of sound in the body are used to create an image. Ultrasound has several medical uses such as scanning babies in the womb, breaking up kidney stones, and physiotherapy. It is safer than x-rays as it does not use ionizing radiation.
VCE Physics Unit 3: Electronics & Photonics Base notesAndrew Grichting
This document provides an overview of key concepts in electronics and photonics covered in a VCE Physics Unit 3 topic. It discusses:
- Applying concepts such as current, resistance, voltage and power to electronic circuits including diodes, resistors, thermistors, light dependent resistors, photodiodes and LEDs.
- Calculating effective resistance of parallel and series circuits and voltage dividers.
- Describing energy transfers in opto-electronic devices and information transfer using light intensity modulation and demodulation.
- Designing, analyzing and investigating circuits for specific purposes using specifications for electronic components.
- Analyzing voltage characteristics of amplifiers and identifying safe practices for electrical and photonic equipment.
Radiation is a form of energy transfer that does not require a medium and travels at the speed of light. Unlike conduction and convection, radiation can transfer heat through a vacuum. All objects emit thermal radiation based on their temperature, with the spectrum and intensity of radiation described by blackbody radiation laws. Radiation transfer is important in applications like solar energy and remote heating/cooling between separated objects.
This document provides an outline for Unit 4 Topic 2 on interactions of light and matter in VCE Physics. It lists key learning outcomes including explaining various phenomena through wave and particle models of light such as the production of incoherent light, Young's double slit experiment, diffraction, the photoelectric effect, electron diffraction, and atomic spectra. Chapter 1 covers the nature of light as electromagnetic radiation and concepts of interference, incoherent versus coherent light sources, and Young's experiment demonstrating the wave-like properties of light. Incandescent light sources produce incoherent light from the random thermal excitation of electrons.
1) The document describes an experiment to determine the Stefan's constant using an incandescent lamp and photovoltaic cell.
2) An incandescent lamp is used as a blackbody radiator, and its temperature is varied. The open circuit voltage of a photovoltaic cell facing the lamp is measured at different temperatures.
3) These voltage measurements are then used in the Stefan-Boltzmann equation to calculate the Stefan's constant. Precise measurements of the lamp's glow resistance and photovoltaic cell voltage are required.
This document provides an overview of magnetism and electromagnetism. It discusses magnetic poles and fields, induced magnetism through electromagnetic induction, and how generators produce alternating current. Moving a magnet or conductor in a magnetic field can induce electric currents according to Faraday's law of induction. The strength of magnetic fields depends on factors like the current flowing and number of wire loops or turns.
The document discusses wave-particle duality and the Davisson-Germer experiment that helped verify this phenomenon. The Davisson-Germer experiment from 1927 fired an electron beam at a nickel crystal and observed that electrons were diffracted at specific angles, providing evidence that electrons exhibit wave-like properties as predicted by de Broglie's hypothesis. This supported the idea in quantum mechanics that particles can behave as both particles and waves, and helped establish the field of quantum mechanics.
1. The document discusses the wave and particle nature of light and provides evidence from phenomena such as interference, diffraction for the wave nature and the photoelectric effect and Compton effect for the particle nature.
2. It then describes the photoelectric effect in detail, explaining terms like threshold frequency, work function, and how Einstein's photoelectric equation explained the instantaneous emission of electrons.
3. Applications of the photoelectric effect include its use in cameras for light meters and in security systems.
Shahjahan notes provides a summary of electrostatics concepts including:
(1) Electric charge can be positive, negative, or neutral and results from an imbalance of protons and electrons in an atom.
(2) Charges can be created through friction or electrostatic induction. A charged object induces opposite charges on nearby uncharged objects.
(3) The basic properties of charge include being quantized, conserved, producing electric fields, and residing on the surface of conductors.
The document discusses the photoelectric effect and its applications. It begins by explaining Einstein's theory that light consists of quantized packets of energy called photons and how this explains the photoelectric effect. It then discusses how the kinetic energy of emitted electrons increases with higher frequency light. The document also provides a simple diagram of a photoelectric experiment and describes some common applications of the effect, including night vision devices, cameras, and smoke detectors. It ends by showing an image and further explaining how photoelectric smoke detectors work by detecting light scattered by smoke particles.
Ionizing radiation can ionize matter directly through charged particles like electrons and protons or indirectly through neutral particles like photons and neutrons. Directly ionizing particles have sufficient kinetic energy to ionize through collisions, while indirectly ionizing particles release directly ionizing secondary particles when interacting with matter. Photons can be attenuated by interactions like the photoelectric effect, Compton scattering, and pair production, with the dominant interaction depending on photon energy. Charged particles interact through Coulomb forces, losing energy through ionization and bremsstrahlung. Neutrons interact primarily through collisions, transferring energy efficiently to heavier nuclei.
This document discusses various topics related to the particle properties of waves, including:
- The photoelectric effect and how photons carry energy in quantized packets.
- Max Planck's quantum hypothesis which established that electromagnetic wave energy is quantized in units of hf.
- Wave-particle duality and how light exhibits both wave and particle behaviors.
- X-rays and how they are produced via the inverse photoelectric effect when electrons are accelerated and strike a metal target.
- The Compton effect which demonstrates that photons can transfer energy and momentum to electrons during scattering.
- Photons, the basic unit of light and electromagnetic radiation which have zero mass but carry energy proportional to their frequency
The document provides information on various topics related to biology. It defines key organelles in plant and animal cells as well as bacteria. It also discusses DNA structure and discovery, genetic engineering, mitosis and meiosis, cloning, stem cells, protein manufacture, mutations, enzymes, and aerobic respiration. The document contains definitions, processes, examples, advantages and disadvantages related to these topics.
The document discusses topics related to chemical reactions and the periodic table. It provides information on:
- Mendeleev's creation of the periodic table and how he arranged elements based on their properties.
- The structure of atoms consisting of protons, neutrons, and electrons located in electron shells around the nucleus.
- The modern periodic table including atomic number and mass number.
- Ionic bonding forming between metals and non-metals through the transfer of electrons. Ionic compounds have high melting/boiling points and conduct electricity when molten or dissolved.
- Covalent bonding forming when atoms share electrons in covalent molecules. Simple covalent substances have low melting/boiling points while giant
The document discusses photocells and how they work to convert sunlight directly into electrical energy by using silicon crystals. When light energy is absorbed by the silicon, electrons are knocked loose, creating an electric current. The power output increases with greater surface area or light intensity. Photocells have advantages like being renewable and producing no pollution or needing fuel, but cannot generate power at night or in bad weather. Solar panels and passive solar heating are also discussed as methods of collecting solar energy and converting it to heat.
A vacuum flask reduces the rate of energy transfer through its design which uses an insulating vacuum between two walls. This prevents convection and conduction from occurring which would otherwise allow the liquid inside to lose heat to its surroundings more quickly.
1) The document discusses various topics relating to physics, including temperature, thermal energy, heat transfer, waves, electromagnetic radiation, communication signals, and ultraviolet radiation.
2) It provides explanations, formulas, and examples for concepts like specific heat capacity, latent heat, reflection, refraction, diffraction, total internal reflection, and analog vs. digital signals.
3) The document also covers applications of these physics principles including fiber optics, lasers, cooking with microwaves and infrared, receiving phone and wireless signals, earthquakes, and the ozone layer.
This a gathering of notes collected from many resources put together to present the content of the AQA GCSE core science physics Unit chapter 5. I made it to help me revise, I jus uploaded it so others can take advantage.
The document provides information on various topics relating to energy transfer and physics, including:
- The three main methods of energy transfer by heating are conduction, convection and radiation.
- Infrared radiation is emitted by all objects and the hotter an object is, the more infrared it emits. Dark, matte surfaces are good absorbers and emitters of infrared.
- Particles have more kinetic energy when they are at higher temperatures, allowing processes like conduction, convection, evaporation and condensation to occur.
- The document also discusses generating electricity, electrical energy, waves, the electromagnetic spectrum, and provides evidence supporting the Big Bang theory of the origin and expansion of the universe.
This document discusses various topics related to physics including:
1) Different types of telescopes like optical, radio, and x-ray telescopes and how they observe different parts of space.
2) The life cycle of stars and how stars like our sun are formed and evolve over time.
3) Red shift phenomenon which provides evidence that the universe is expanding as galaxies move further away from us.
4) Different types of waves like infrasound, ultrasound, seismic waves and how they are used to detect volcanoes, do pre-natal scans, and examine the inner structure of the Earth.
Ultrasound uses high frequency sound waves to create images of the inside of the body. It works by sending sound waves into the body which bounce off organs and tissues and are detected by the ultrasound machine. The time it takes for the echo to return and the speed of sound in the body are used to create an image. Ultrasound has several medical uses such as scanning babies in the womb, breaking up kidney stones, and physiotherapy. It is safer than x-rays as it does not use ionizing radiation.
VCE Physics Unit 3: Electronics & Photonics Base notesAndrew Grichting
This document provides an overview of key concepts in electronics and photonics covered in a VCE Physics Unit 3 topic. It discusses:
- Applying concepts such as current, resistance, voltage and power to electronic circuits including diodes, resistors, thermistors, light dependent resistors, photodiodes and LEDs.
- Calculating effective resistance of parallel and series circuits and voltage dividers.
- Describing energy transfers in opto-electronic devices and information transfer using light intensity modulation and demodulation.
- Designing, analyzing and investigating circuits for specific purposes using specifications for electronic components.
- Analyzing voltage characteristics of amplifiers and identifying safe practices for electrical and photonic equipment.
Radiation is a form of energy transfer that does not require a medium and travels at the speed of light. Unlike conduction and convection, radiation can transfer heat through a vacuum. All objects emit thermal radiation based on their temperature, with the spectrum and intensity of radiation described by blackbody radiation laws. Radiation transfer is important in applications like solar energy and remote heating/cooling between separated objects.
This document provides an outline for Unit 4 Topic 2 on interactions of light and matter in VCE Physics. It lists key learning outcomes including explaining various phenomena through wave and particle models of light such as the production of incoherent light, Young's double slit experiment, diffraction, the photoelectric effect, electron diffraction, and atomic spectra. Chapter 1 covers the nature of light as electromagnetic radiation and concepts of interference, incoherent versus coherent light sources, and Young's experiment demonstrating the wave-like properties of light. Incandescent light sources produce incoherent light from the random thermal excitation of electrons.
1) The document describes an experiment to determine the Stefan's constant using an incandescent lamp and photovoltaic cell.
2) An incandescent lamp is used as a blackbody radiator, and its temperature is varied. The open circuit voltage of a photovoltaic cell facing the lamp is measured at different temperatures.
3) These voltage measurements are then used in the Stefan-Boltzmann equation to calculate the Stefan's constant. Precise measurements of the lamp's glow resistance and photovoltaic cell voltage are required.
This document provides an overview of magnetism and electromagnetism. It discusses magnetic poles and fields, induced magnetism through electromagnetic induction, and how generators produce alternating current. Moving a magnet or conductor in a magnetic field can induce electric currents according to Faraday's law of induction. The strength of magnetic fields depends on factors like the current flowing and number of wire loops or turns.
The document discusses wave-particle duality and the Davisson-Germer experiment that helped verify this phenomenon. The Davisson-Germer experiment from 1927 fired an electron beam at a nickel crystal and observed that electrons were diffracted at specific angles, providing evidence that electrons exhibit wave-like properties as predicted by de Broglie's hypothesis. This supported the idea in quantum mechanics that particles can behave as both particles and waves, and helped establish the field of quantum mechanics.
1. The document discusses the wave and particle nature of light and provides evidence from phenomena such as interference, diffraction for the wave nature and the photoelectric effect and Compton effect for the particle nature.
2. It then describes the photoelectric effect in detail, explaining terms like threshold frequency, work function, and how Einstein's photoelectric equation explained the instantaneous emission of electrons.
3. Applications of the photoelectric effect include its use in cameras for light meters and in security systems.
Shahjahan notes provides a summary of electrostatics concepts including:
(1) Electric charge can be positive, negative, or neutral and results from an imbalance of protons and electrons in an atom.
(2) Charges can be created through friction or electrostatic induction. A charged object induces opposite charges on nearby uncharged objects.
(3) The basic properties of charge include being quantized, conserved, producing electric fields, and residing on the surface of conductors.
The document discusses the photoelectric effect and its applications. It begins by explaining Einstein's theory that light consists of quantized packets of energy called photons and how this explains the photoelectric effect. It then discusses how the kinetic energy of emitted electrons increases with higher frequency light. The document also provides a simple diagram of a photoelectric experiment and describes some common applications of the effect, including night vision devices, cameras, and smoke detectors. It ends by showing an image and further explaining how photoelectric smoke detectors work by detecting light scattered by smoke particles.
Ionizing radiation can ionize matter directly through charged particles like electrons and protons or indirectly through neutral particles like photons and neutrons. Directly ionizing particles have sufficient kinetic energy to ionize through collisions, while indirectly ionizing particles release directly ionizing secondary particles when interacting with matter. Photons can be attenuated by interactions like the photoelectric effect, Compton scattering, and pair production, with the dominant interaction depending on photon energy. Charged particles interact through Coulomb forces, losing energy through ionization and bremsstrahlung. Neutrons interact primarily through collisions, transferring energy efficiently to heavier nuclei.
This document discusses various topics related to the particle properties of waves, including:
- The photoelectric effect and how photons carry energy in quantized packets.
- Max Planck's quantum hypothesis which established that electromagnetic wave energy is quantized in units of hf.
- Wave-particle duality and how light exhibits both wave and particle behaviors.
- X-rays and how they are produced via the inverse photoelectric effect when electrons are accelerated and strike a metal target.
- The Compton effect which demonstrates that photons can transfer energy and momentum to electrons during scattering.
- Photons, the basic unit of light and electromagnetic radiation which have zero mass but carry energy proportional to their frequency
The document provides information on various topics related to biology. It defines key organelles in plant and animal cells as well as bacteria. It also discusses DNA structure and discovery, genetic engineering, mitosis and meiosis, cloning, stem cells, protein manufacture, mutations, enzymes, and aerobic respiration. The document contains definitions, processes, examples, advantages and disadvantages related to these topics.
The document discusses topics related to chemical reactions and the periodic table. It provides information on:
- Mendeleev's creation of the periodic table and how he arranged elements based on their properties.
- The structure of atoms consisting of protons, neutrons, and electrons located in electron shells around the nucleus.
- The modern periodic table including atomic number and mass number.
- Ionic bonding forming between metals and non-metals through the transfer of electrons. Ionic compounds have high melting/boiling points and conduct electricity when molten or dissolved.
- Covalent bonding forming when atoms share electrons in covalent molecules. Simple covalent substances have low melting/boiling points while giant
The early atmosphere on Earth was formed by gases released from volcanic eruptions. The main gases were carbon dioxide, nitrogen, water vapor, and ammonia, with little to no oxygen. Over time, carbon dioxide levels fell as it dissolved in the oceans and was incorporated into marine organisms' shells. As plant life increased through photosynthesis, oxygen levels rose and carbon dioxide levels fell further. Rocks can provide information about the early atmosphere by analyzing their mineral composition and looking for oxide formations that indicate higher oxygen levels over time.
This document provides information on qualitative and quantitative analysis of ions in water samples. It discusses common cation and anion tests including flame tests for metals, reactions of halogens with silver nitrate, and tests for ammonium ions. Methods are described for identifying unknown ions in a sample. Ion identification is important in industries such as water treatment and medical testing. The document also covers types of water, calculating concentration, and identification of ions through precipitation reactions and other common tests.
1. The document discusses the classification of living organisms from species to kingdoms. Organisms are classified based on characteristics like cellular structure, nutrition, and habitat.
2. It also covers homeostasis and how organisms maintain stable internal conditions through processes like thermoregulation and osmoregulation in response to stimuli. Sensory neurons detect stimuli and transmit signals to the central nervous system to trigger responses.
3. Darwin's theory of evolution by natural selection is summarized as involving variation, overproduction, competition, survival of advantageous traits which are passed on, leading to gradual change over generations.
This document discusses classification of living organisms and influences on life. It covers the five kingdoms, classification of vertebrates including chordates, and difficulties in classification. Key terms like species, binomial system, variation and evolution are defined. The roles of genes, inheritance, and genetic disorders are also addressed.
Circadian rhythms and photoperiodism are important control systems in plants and animals. Circadian rhythms cause daily fluctuations in processes like melatonin production, while photoperiodism causes responses to changing day length like seed germination and flowering. Plants have evolved defenses against pathogens like producing toxic chemicals, and humans have exploited these by using plant-derived medicines. The immune system provides protection through acquired immunity from vaccines and antibodies from monoclonal antibodies. Key body systems like the kidneys and menstrual cycle are regulated by negative feedback of hormones.
(1) The document provides information on biology revision cards covering topics such as classification, kingdoms, adaptation, thermoregulation, drugs, and pathogens.
(2) It discusses the five kingdoms and characteristics of each, as well as classification hierarchies from phylum down to species. Principles of Darwin's theory of evolution are also summarized.
(3) Thermoregulation in humans and plants is explained, covering processes like vasodilation, hypothalamus function, and plant hormones. Impacts of drugs like cigarettes and alcohol are also outlined.
This document contains summary notes on chemistry topics for a GCSE science course. It covers the fundamental ideas in chemistry including atoms, the periodic table, and chemical reactions. It also discusses specific topics like limestone and building materials, metals and their uses, crude oil and fuels, and plant oils. For each topic, it provides an overview and defines key terms and concepts.
The document discusses the history of models of the solar system from Ptolemy's geocentric model to Copernicus' heliocentric model, which Galileo later provided evidence for using a telescope. It also describes how telescopes have improved over time and allowed for the discovery of more planets and insights into the solar system and beyond. Modern observations show there are billions of galaxies in the universe and our sun is one of millions of stars in the Milky Way galaxy.
Photosynthesis has two stages: (1) the light-dependent stage where chloroplasts use light energy to produce ATP and NADPH, and (2) the light-independent stage where carbon dioxide is fixed into carbohydrates using ATP and NADPH. During the light-dependent stage, light is absorbed by chlorophyll, electrons are transferred through an electron transport chain to produce ATP, and water is split to provide electrons that reduce NADP to NADPH. The light-independent stage can continue in the dark using ATP and NADPH to reduce carbon dioxide into carbohydrates like glucose.
A Brief Introduction to Mannose-Binding Lectin (MBL) and its Clinical Signifi...Katie B
An old research project conducted at Queen Mary's Childrens Hospital (St Helier's Hospital) thanks to Nuffield. This is a summary of my research into mannose-binding lectin.
This document presents information about electric charge and how it moves through circuits. It discusses conductors and insulators, how charge can be given to objects through friction, and how like charges repel and opposite charges attract. Examples of electrostatic induction and applications of static electricity like photocopiers, inkjet printers, van de Graaff generators, and electrostatic painting and precipitation are also summarized. The document encourages exploring simulations on electric charge at the provided website for more learning.
How Complement System Works (Lectin Pathway)Katie B
The lectin pathway is part of the complement system, which is part of the innate immune system. It acts as the first line of defense against microbes entering the body. In the lectin pathway, MBL attaches to mannose on microbes. This activates the complement system by breaking down C4 and C2 proteins to form a C3 convertase, which then breaks down C3 into C3b and C3a. C3b opsonizes the microbe while C3a causes inflammation. C3b then binds to the microbe and C3 convertase to form a C5 convertase, continuing the complement cascade and ultimately forming a membrane attack complex that causes cell lysis of the micro
Bacteria are prokaryotic organisms that can be pathogens or beneficial. They have a cell wall, capsule, membrane, flagella, pili, mesosomes, and DNA. Viruses contain nucleic acid and a protein coat, some with an envelope. Bacteria replicate through cell division while viruses have two life cycles - lysogenic involves integrating viral DNA into the host and lytic involves hijacking the host to produce new virus particles. The document compares the components of bacteria and viruses.
GCSE Chemistry Revision - Air and Air PollutionKatie B
The document discusses air pollution and the composition of Earth's atmosphere over time. It explains that Earth's early atmosphere contained mostly carbon dioxide and nitrogen, but after plants evolved and began producing oxygen through photosynthesis, oxygen levels rose and carbon dioxide levels fell. It also discusses how burning fossil fuels increases carbon dioxide in the atmosphere and has led to issues like acid rain from sulfur pollution, global dimming from smoke particles, and global warming due to the greenhouse effect of carbon dioxide and other gases. The document recommends ways to reduce pollution from vehicles, such as using catalytic converters to change nitrogen oxides and carbon monoxide from exhaust into less harmful gases.
Buffers are used in soap to neutralize it, in cosmetics like skin creams to regulate the pH of alpha-hydroxy-acids, and also play an important role in regulating blood pH.
The document discusses static electricity and electrostatics. It explains that:
- Charged objects can be charged through friction or induction. Friction charging involves the transfer of electrons, while induction charging uses the redistribution of existing electrons in a conductor.
- Like charges repel and unlike charges attract, following Coulomb's law. The direction and strength of electric fields can be represented by field lines.
- Applications include photocopiers, which use photoconductivity and electrostatic attraction/repulsion to transfer toner images to paper. Hazards include lightning and electrostatic discharge damaging electronics.
- Electrical accidents are a major cause of deaths globally each year, with over 400 deaths from job-related electrical accidents in the US alone. Common causes of accidents include working on live equipment without protection and wiring mistakes.
- Standards for electrical safety are evolving globally, with organizations like NFPA and OSHA developing codes to reduce accidents. Devices like RCCBs that detect small leaks are also being more widely used.
- It is important to inspect electrical equipment regularly, use protective equipment when working with electricity, and follow lockout/tagout procedures to isolate energy sources before repair to avoid accidents.
This document provides information on various biology topics in outline form:
- Insulin and glucose regulation in the liver
- Aerobic and anaerobic respiration and their differences
- Factors that affect pulse rate and blood pressure during exercise
- The roles of carbohydrates, fats, proteins, vitamins and fiber in digestion
- Calculation of Body Mass Index (BMI)
- The process of digestion and the roles of enzymes
- Types of immune responses against pathogens
- Structure and function of the eye, including accommodation and common vision defects
- Structure and function of neurons, synapses, and reflex arcs
- Effects and risks of stimulant and depressant drugs
- Negative feedback loops to maintain
The document provides information about various topics related to energy and earth science. It discusses different forms of energy including kinetic energy, potential energy, mechanical energy, chemical energy, and others. It also explains different methods of heat transfer including conduction, convection, and radiation. Additionally, it covers topics like renewable and non-renewable energy sources, properties of light and sound, electricity, circuits, the solar system, seasons, and tides.
Electrostatics covers the properties of electric charges, electrostatic force, and electric fields. Key points include:
- There are two types of electric charges: positive and negative. Like charges repel and unlike charges attract.
- Charge is quantized and conserved. It exists in integer multiples of the fundamental unit, e.
- Coulomb's law describes the electrostatic force between two point charges. The force is proportional to the product of the charges and inversely proportional to the square of the distance between them.
- Electric fields are vector fields that exist around charged objects. The electric field strength is defined as the force per unit charge. Field lines are used to represent electric fields graphically.
The document provides an overview of a physics course for chemical engineers. It includes information on course format, learning activities, grading, and course content. The course format involves lectures where the instructor presents material and interactive problem solving sessions. Learning activities include lectures, private study, and completing tutorial questions. Grading is based on homework, quizzes, two sessionals, and a terminal exam. Course content covers topics like electrostatics, magnetostatics, electric circuits, electromagnetic induction, and optics.
The document discusses charging by friction and static electricity. Rubbing a glass rod strips electrons from some of its surface atoms, giving those atoms a positive charge and the rod an overall positive charge. Other materials like polythene are given a net negative charge when electrons are rubbed off onto them. Like charges repel and opposite charges attract, according to the electrostatic law.
The document provides a summary of physics concepts for exam revision. It includes 27 questions and answers covering topics like work function, secondary emission, atomic structure, electricity, magnetism, sound waves, optics, heat, and forms of energy. Key points explained include how a low work function allows easier electron emission from a cathode, how secondary emission occurs when primary electrons hit a surface, and the use of step-up transformers in power transmission.
1. Electric charges can be positive or negative, and electric forces cause like charges to repel and unlike charges to attract according to Coulomb's Law.
2. Atoms contain protons with a positive charge and electrons with a negative charge; objects are neutral when they contain equal numbers of protons and electrons.
3. Electric fields are created by electric charges and describe the interaction of electric forces; electric fields can be used to accelerate electrons in devices like x-ray machines and televisions.
4. Capacitors are used to store electric charge and consist of conductive plates separated by an insulator; the amount
1. Electricity is the flow of electrons through a conductor. It is measured as an electric current in Amperes.
2. An electric field is the region surrounding an electric charge where other charges will experience a force. Electric field lines extend from positive charges and terminate at negative charges.
3. Examples of electric fields can be seen through the behavior of flames in an electric field and the spreading of hair charged by a Van de Graaf generator.
Kinetic energy is the energy of moving objects. When a ball is thrown up, gravity converts the kinetic energy into potential energy. Gravity is directed downward with an acceleration of 9.8 m/s2. The two types of electric charge are positive and negative. Charged objects become charged through friction, conduction, or induction which leads to electric forces and fields between them.
Kinetic energy is the energy of moving objects. When a ball is thrown up, gravity converts the kinetic energy into potential energy. Gravity is directed downward with an acceleration of 9.8 m/s2. The two types of electric charge are positive and negative. Charged objects become charged through friction, conduction, or induction which leads to electric forces and fields between them.
This document provides an introduction to electrostatics and electric fields. It defines key terms like electric charge, conductors, insulators, and dielectrics. It describes methods of charging including rubbing, conduction, and induction. Coulomb's law is explained, as well as the properties of electric fields including field lines and flux. Gauss's law relating electric flux to enclosed charge is described. Applications of Gauss's law to find electric fields due to infinite line charges, thin sheets of charge, and spherical shells are provided. Several practice problems are included at the end.
This document introduces the topic of electrostatics and electric charges and fields. Some key points include:
- Electrostatics deals with static electric charges and the forces, fields, and potentials arising from them. Charges can be positive or negative.
- The electric field is a vector quantity that describes the force exerted on a charge in a given point in space. It is calculated using Coulomb's law and the superposition principle.
- Electric field lines are imaginary lines used to depict electric fields graphically. They originate on positive charges and terminate on negative charges.
- Gauss's law relates the electric flux through a closed surface to the net charge enclosed by the surface. It can be used to calculate electric
1. The document defines key terms related to electromagnetism and static electricity, such as charge, conductors, insulators, and electrical discharge.
2. It describes circuit components like batteries, switches, resistors, and meters. Equations for voltage, current, resistance, and power are given.
3. The document addresses electric fields, magnetic fields, and how to determine current and magnetic field directions using the right hand grip rule. It also covers how magnetic field strength is affected by current and distance from the wire.
Static electricity results when electrons are transferred between objects, leaving one object with a net positive charge and the other with a net negative charge. Materials are made of atoms containing protons, neutrons, and electrons. Insulators have few free electrons, while conductors have many, allowing charge to flow more easily. Unlike charges attract due to their opposite polarity, while like charges repel. Electrostatics has applications including photocopiers, spray painting, and electrostatic precipitators that remove particles from emissions.
The document discusses the basics of electricity, including:
- Electricity is the flow of electric charge caused by the movement of electrons.
- Atoms are made up of protons, neutrons, and electrons. Electrons moving between atoms creates electric current.
- Voltage is the difference in electric potential/charge between two points, current is the flow of charge, and resistance opposes the flow of current.
- Static electricity involves a build up of charges on insulated objects, while current electricity flows through a closed circuit. Alternating current periodically changes direction while direct current flows one way.
This document discusses conductivity and mobility in semiconductors. It explains that an applied electric field causes charge carriers like electrons to drift in a direction, with their drift velocity depending on mobility. Mobility decreases with increasing temperature or impurity concentration. The document also covers how conductivity is calculated from charge carrier concentration and mobility, and how the Hall effect can be used to determine these parameters by applying a magnetic field.
This document provides notes on electrostatics. It defines key terms like electrostatics, electric charge, conductors, insulators, semiconductors. It describes properties of electric charge including additivity, quantization, and conservation. Coulomb's law is explained, relating the electrostatic force between two point charges to the product of their charges and the inverse square of the distance between them. The document also compares electrostatic force and gravitational force.
Chapter 1-Basic concept in physics-2022-2023- final.pptxHalaHaladaqqa
This document provides an overview of the key concepts that will be covered in a course on basic biomechanics and physics. It includes:
1. An introduction to SI units and physics quantities.
2. Sections on translation and rotational motion of objects, forces and Newton's laws of motion, work, energy, power, pressure, and hydrostatic pressure.
3. A brief outline of the chapters, including mechanics concepts like kinematics, dynamics, statics, and fluids as well as electricity and magnetism fundamentals.
This is a ppt which is based on electricity chapter of class 10 in science ncert cbse book . it will definitely enhance your knowledge and clear all concepts about this chapter .
Here are the steps to solve this problem:
1) Find the force between qA and qB using Coulomb's Law:
FAB = k(qAqB/dAB^2) = (8.99x10^9 Nm^2/C^2)(-7.27x10-9 C)(12.36x10-9 C)/(4x10-5 m)^2 = -1.15x10-14 N
2) Find the force between qB and qC:
FBC = (8.99x10^9 Nm^2/C^2)(12.36x10-9 C)(-5.18x10-9 C)/(
Here are the steps to solve this problem:
1) Find the force between qA and qB using Coulomb's Law:
FAB = k(qAqB/dAB^2) = (8.99x10^9 Nm^2/C^2)(-7.27x10-9 C)(12.36x10-9 C)/(4x10-5 m)^2 = -1.14x10-11 N
2) Find the force between qB and qC:
FBC = (8.99x10^9 Nm^2/C^2)(12.36x10-9 C)(-5.18x10-9 C)/(
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
2. Proton Neutron Electron
Charge +1 0 -1
Mass 1 1 0.0005 (almost zero)
The charge and mass of electrons, protons and
neutrons
P2.1 Static Electricity
Protons = positively charged
Electrons = negatively charged.
Electrons are in the shells of atoms.
Charge of an atom = neutral as the + and the – are equal.
Static electricity
In insulator can become charged by friction through the transfer of electrons.
A substance that gains electrons becomes negatively charged, while a substance that loses
electrons becomes positively charged.
When a charged object comes near to another object they will either attract or repel each
other.
If the charges are the same - they repel
If the charges are opposite - they attract
3. P2.1 Electrostatic Phenomena
The negatively charged balloon
repels the electrons in the wall
and they move away. The
positive charge left behind
attracts the balloon.
The negatively charged comb repels
the electrons in the paper. The
positive charge left behind is attracted
to the comb which is why it picks up
the paper.
4. P2.2 Uses and Dangers of static
How lightning is caused:
• Static electricity can build up in clouds. This can cause a huge spark to form between
the ground and the cloud.
• A flow of charge through the atmosphere.
Static is dangerous when:
• There are inflammable gases or vapours or a high concentration of oxygen. A spark
could ignite the gases and cause an explosion.
• You touch something with a large electric charge on it. The charge will flow through
your body causing an electric shock.
Static electricity builds up on everyday objects. It can be dangerous if it can create a
spark. A conducting path can be used to prevent sparking.
Earthing removes excess charge by
movement of electrons.
The electrons flow through the earthing
cable to earth rather than there being a
discharge and spark.
5. Paint Spraying
1) The car is negatively charged.
2) The paint is positively charged. The positively
charged paint spreads out as the repel each other.
3) The negative attracted to the positive and stick.
4) The metal spray nozzle is connected to the positive
terminal of the power pack and the paint picks up a
positive charge.
Air craft can build up a static charge when flying through the air and refuelling can also
build a charge. To stop explosions the aircraft has a bonding line which is used to
connect the air craft to the earth before it has been refuelled.
Insecticide sprays
Insecticide use static electricity.
Sprayed from aircraft so that they cover a large area.
Risk that some of the spray will blow away or fall unevenly. To prevent this, the insecticide is given
a static charge as it leaves the aircraft.
The static drops spread evenly as they all have the same charge and are attracted to the earth.
P2.2 Uses and Dangers of static
6. P2.3 Electric Currents
Materials contain electrons.
Insulating materials the electrons cannot move but in a metal they move and
this can and this creates a current.
Be able to use the equation:
charge (coulomb, C) = current (ampere, A) x time (second, s)
Q = I x t
Key terms
• Current is the flow of charge
• Current in metals is the flow of electrons
• Cells and batteries supply direct current
(d.c.)
• Direct current is the movement of charge in
one direction.
7. Voltmeter Ammeter
Measures voltage in
Volts
Measures current in
Amps
Measures the energy
difference between the
electrons going into the
component and back.
Electrons not used up
out the output is the
same as the input back
to the cell.
Parallel Series
No junctions Current splits up at a
junction
Potential difference
measured.
Current size measured.
P2.4CurrentandVoltage.
Potential difference is the
energy transferred per
unit charge.
1 Volt is 1 Joule per
Coulomb
8. P2.6 Changing resistances
• Resistance measures how hard it is for the electricity to flow through a
circuit.
• Measured in Ohms
• Dependant on how many components are in the circuit.
• The higher the resistance the lower the current.
• Variable resistor = can change the resistance of a wire.
Component Resistance
Filament lamp. As they get hot the resistance decreases. They get hot as they have a higher potential
difference.
Diodes Electricity flows in one direction. If a potential difference is applied in the other direct no
current will flow.
Light dependant resistor Resistance is high in the dark and low in the day time
Thermistor High resistance when cold, low resistance when hot.
Be able to use the equation:
potential difference (volt, V) = current (ampere, A) x resistance (ohm, Ω)
V = I x R
10. P2.7 Transferring energy
Equations you must be able to use
Calculating Electrical Power
electrical power (watt, W) = current (ampere, A) x potential difference (volt, V)
P = I x V
Energy transferred (joule, J) = current (ampere, A) x potential difference (volt, V) x time (second, s)
E = I x V x t
Distinguish between the advantages and
disadvantages of the heating effect of an
electric current
Advantages Disadvantages
Useful Heating a
kettle
Wasted energy
Useful in Fires Cause burns
A current in a wire is a flow of electrons . As the electrons move in a metal they collide
with the ions in the lattice and transfer some energy to them.
This is why a resistor heats up when a current flows through.
12. Vectors and Velocity
Quantities which have a direction and size are known as VECTOR QUANTITIES.
4 Examples
• Displacement – distance travelled in a particular direction.
• Velocity – speed in a particular direction.
• Force – always has a size and direction.
• Acceleration – it has size and direction
Speed (m/s) = distance (m) ÷ time (s)
Acceleration (m/s2) = change in velocity (m/s) ÷ time (s)
Key equations you need to be able to use:
13. Distance/Time Graphs
• Horizontal lines mean the
object is stationary.
• Straight sloping lines mean
the object is travelling at a
constant speed.
• The steeper the slope, the
faster the object is
travelling.
• A curved line means
acceleration.
• To work out the
acceleration, you need to
calculate the gradient.
14. Velocity/Time Graph
• Horizontal lines mean the
object is travelling at a constant
velocity.
• Straight sloping lines mean the
object is accelerating or
decelerating.
• The steeper the slope, the
faster the acceleration.
• A curved line means
acceleration.
• The area under the graph is the
distance travelled.
15. Forces
A force is a push or a pull.
When two bodies interact, the forces they exert on each other are
equal in size and opposite in direction. These are known as REACTION
FORCES.
You need to be able to
interpret these diagrams
and work out the
resultant force in each
direction.
If the resultant force is zero, it will remain at rest or continue to travel
at a constant speed.
If the resultant force is not zero, it will accelerate in the direction of
the resultant force.
16. Forces and Acceleration
The size of
acceleration
depends on:
• Size of the
force
• Mass of the
object
Key equation you
need to be able
to use:
Force (N) = Mass
(kg) x acceleration
(m/s2)
17. In a vacuum
• all falling bodies accelerate at the same rate.
In the atmosphere
• Air resistance increases with increasing speed.
• Air resistance will increase until it is equal in size to the weight of a falling
object.
• When the two forces are balanced, acceleration is zero and TERMINAL
VELOCITY is achieved.
Terminal Velocity
Key equation you need to be able
to use:
Weight (N) = Mass (kg) x gravity (N/kg)
19. Stopping Distances
Stopping distance = thinking distance + breaking distance
6 Factors affecting stopping
distance:
1. Mass of vehicle
2. Speed of vehicle
3. Drivers reaction time
4. State of the breaks
5. State of the road
6. Amount of friction between
the tyre and the road
surface.
5 Factors affecting reaction time:
1. Age of driver
2. Drugs e.g. alcohol
3. Visibility
4. Tiredness
5. Distractions
Investigating friction. How
much force is needed to move
weights on different surfaces?
20. Momentum
A measure of motion. Mass multiplied by velocity.
When a moving object collides with another object, the momentum is
the same before the collision as it is after the collision.
21. Momentum and Safety
When you are travelling in a car (or on a bike, skis, train etc.) you are
travelling at the same speed as the car. If the car stops suddenly, your
momentum continues to carry you forward. If you are stopped
suddenly, by hitting the dashboard (or ground) you experience a large
force, and therefore a large amount of damage.
Car safety features:
1. Seatbelts – stretch to increase the time taken to stop, thus reducing the rate of
change of momentum and reducing injury
2. Air bags – inflate to increase the time taken to stop, thus reducing the rate of
change of momentum and reducing injury
3. Crumple Zones – crumple and fold in a specific way to increase the time taken to
stop, thus reducing the rate of change of momentum and reducing injury
Use this formula:
Force (N) = change in momentum ÷ time
If you increase the time you
reduce the force.
22. Work and Power
Key definitions
• Work – the amount of energy transferred. Measured in Joules (J)
• Power – The rate of doing work. Measured in Watts (W). 1 joule per
second is 1 watt.
Use this formula:
Work Done (J) = Force (N) x distance moved (m)
Example – if a 1kg mass (10N) is moved through a distance of 2 metres the work done
is 20J.
Use this formula:
Power (W) = Work Done (J) ÷ Time taken (s)
Example – if a 24J of work is done over a 30 second period, the Power would be 24 ÷
30 = 0.8W
23. Potential and Kinetic Energy
You need to be able to use these
equations:
GPE = mgh
KE = ½mv2
Key Definitions
• Kinetic Energy – movement energy
• Gravitational Potential Energy – the energy something has due to its position relative
to Earth – i.e. its height.
Conservation of Energy
When energy is transferred, the
total amount always remains the
same.
25. P2.23 Isotopes
Keywords
• Sub-atomic particles – a particle that is smaller than an atom
• Nucleons – The subatomic particles in the nucleus of an atom e.g. protons and neutrons
• Isotopes – Atoms of an element with the same number of protons and electrons but with a
different number of neutrons.
Remember
• The Mass number is More that
the atomic number
Atoms
• Atoms contain electrons, protons and neutrons = subatomic particles
• Protons and Neutrons in the nucleus = they are called nucleons
• All atoms on one element have same number of protons = atomic number
• Mass number = number of protons and neutrons in the nucleus
Isotopes
• Atoms with different number of neutron (same number of protons)
• Different mass numbers
• Examples
– Lithium – 6 and Lithium-7
– Carbon-12 and Carbon-14
• An atom with a number attached referred to the isotope (as above)
26. Ionising radiation
Keywords
• Unstable – an unstable nucleus is one that will decay and give out ionising radiation
• Radioactive Decay – when an unstable nucleus changes by giving out ionising radiation
to become more stable
• Ion - An atom with an electrical charge (through loss or gain of electrons)
P2.24 Ionising radiation
Alpha Beta Gamma
• Particles containing 2 protons
and 2 neutrons (Helium atom
nucleus)
• No electrons = 2+ charge
• Emitted from nucleus at high
speed
• Lose energy as they ionise an
atom
• Produce many ions quickly so
have short penetration
distance
• Stopped by a few cm of air of
mm of paper
• Electrons that are
emitted from an
unstable nucleus
• Much less ionising that
alpha
• Can penetrate much
further into matter
• Stopped by a few mm or
aluminium or even
thinner lead.
• High-frequency
electromagnetic waves
emmited by unstable
nuclei
• Travel at the speed of
light
• Ten times less ionising
that beta
• Penetrate matter easily
• Stopped by a few cm of
lead or many metres of
concrete.
27. P2.25 Nuclear reactions
Keywords
• Nuclear fission– the splitting on a large nucleus.
• Nuclear fusion – the joining of two small nuclei
Nuclear Fission
• Nucleus splits into two smaller nuclei
• Two or more neutrons also released
• NOT the same as radioactive decay
• If neutron are absorbed by other nuclei it can make them unstable – they then
split releasing more nuclei = chain reaction (like an atomic bomb.
• Can be controlled with materials to absorb neutrons (like in a nuclear reactor)
Radioactive Decay
• Releases energy
• Alpha and Beta = kinetic energy
• Gamma = energy in form of electromagnetic
radiation
Nuclear Fusion
• Small nuclei can combine to
form larger ones
• Also releases a lot of energy
28. P2.26 Nuclear power
Nuclear Reactors
• Transform energy contained in nuclei of uranium and plutonium into thermal energy
• Nuclear fission
• Pellets of uranium inserted into hollow rods
• Rods place in reactor core
• Rate is kept constant but controlling the chain reaction
• Number of free neutrons will not increase of decrease
• Extra neutrons absorbed by control rods
• Control rods placed in between fuel rods in reactor core
• Control rods can be moved in and out to change the rate of fission
• Fully lowered they shut down the reactor.
Keywords
• Moderator – a substance in
a nuclear reactor which
slows down neutrons so that
they can be absorbed by the
nuclear fuel more easily.
• Radioactive waste –
Material left over after the
fission of uranium that is
radioactive
Generating electricity
• Thermal energy from core is transferred to coolant
(usually water)
• Coolant pumped through reactor
• Coolant at high pressure pumped to heat exchanger to
produce steam
• Steam drives turbine which turns generator
• Generator transfers kinetic energy to electrical energy.
29. P2.27 Fusion – our
future?
Keywords
Peer reviewed – work checked by different scientists working in the
same field
Validate – to confirm scientific theory is true
• Scientists investigating fusion to generate electricity
• The helium produced is not radioactive
• Materials used to contain fusion do become radioactive
Getting new ideas accepted
• Scientific theories have to be validated
• By the scientific community
• Report and results are peer-reviewed
• Other scientists must carry out the experiment and get the same results
Fusion and temperature
• The nuclei that fuse are both positively charged so repel = electrostatic repulsion
• Nuclei need to be extremely close
• High density nuclei are more likely to collide e.g. in the Sun the high gravitational field creates high
density nuclei.
• Difficult condition to create on earth
• Fusion reactors try to produce high pressures and high temperature
• High temperatures = more kinetic energy to overcome repulsion and collide.
• These conditions require a lot of energy (more than the reactor can make so currently not very
efficient)
31. P2.28 Changing ideas
Henri Becquerel and Marie Curie
• Accidental discovery was made that Uranium exposed photographic plates =
discovery of radioactivity
• Showed how radiation could ionise gases
• Skin burns visible from handling Radium
• By 1920s links made with cancer (Marie Curie died of lukaemia)
• Large amount of ionising radiation = tissue damage (radiation burns)
• Smaller amounts regularly = DNA damage (mutations)
• Some mutations lead to cancer
Keywords
Hazards – causes of harm
Risk – likelihood of harm
Mutation – a change in the base sequence of DNA.
Handling radioactive sources
• Risk of harm decreases with distance from the source
• Sources always handled with tongs
• Risk reduced by not pointing sources at people
• Keep sources in lead lined containers
32. P2.29 Nuclear Waste
High level waste
• The fission products from Uranium fuel are very radioactive
• Produces large amounts of ionising radiation for about 50
years
• Remains moderately radioactive for thousands of years as
intermediate level waste
• Transported in thick concrete and steel containers
• Sealed in glass to prevent escape
• Stored in canisters until it becomes ILW
Intermediate level waste
• Remains moderately radioactive for
thousands of years
• Includes the metal cylinders that contained
uranium fuel which become radioactive
• Stored in concrete and steel containers
• None disposed of yet
Low level Waste -
• Only slightly radioactive
• Remains so for tens of thousands of years
• Clothing and cleaning materials from nuclear power
stations
• Hospitals also a source of LLW from radiotherapy
cancer treatments
• Compacted and buried in special landfill
Advantages of nuclear power Disadvantages of nuclear power
• Station does not produce CO2
• Less impact on global warming
• Making the fuel rods requires energy (CO2 released)
• Waste has to be stored for tens of thousands of years without
leaks
• People perceive it as unsafe after the Chernobyl accident
Disposal methods
1. Firing into space
– Risk of it falling back
2. Dumping in barrels at sea
– Barrels can corrode
– Enters food chain
3. Storage underground
– Need geologically stable site
– Low earthquake risk
33. P2.30 Half-life
Radioactive decay
• Unstable nucleus undergoes radioactive
decay to become more stable
• Activity of a substance is the number of
nuclear decays per second
• Measure in becquerel (Bq)
• 1Bq is one nuclear decay each second
• Radioactive decay is a random process
(cannot predict it)
• Half life = the time taken for half the
unstable nuclei in a sample of a radioactive
isotope to decay.
• Half life does not change as the sample gets
smaller
• After decaying = more stable nucleus
• More stable nucleus = lower activity
• Half life found by recording activity over a
period of time.
Geiger-Muller tube
• Used to measure radioactivity
• Can be connected to a counter or may
give a click when radiation detected
• Count rate = number of clicks per
second or minute
34. P2.32 Background radiation
Keywords
• Background radiation – ionising radiation that is around us all the time from a number of sources.
Some is naturally occurring.
• Background count – the average number of counts recorded by a GM tube in a certain time from
background radiation
• Radon gas – naturally occurring radioactive gas that is emitted from rocks as a result of the decay of
radioactive uranium
Background Radiation
• Main source = radon gas
• Released from decaying uranium in rocks
• Diffuses into the air from rocks and soil
• Medical sources = x-rays; gamma rays (scans) and cancer treatments
• Some food are naturally radioactive
• Cosmic rays = high energy charged particles from the stars (like the Sun) and supernovae,
neutron stars and black holes.
• Many cosmic rays are stopped by the atmosphere but some reach Earth.
• We are constantly exposed to ionising radiation – from space and naturally occurring = background
radiation
• Needs to be considered when measuring a source
• Background count is subtracted from the source count
35. P2.33 and P2.34 Uses of radiation
Treatment of Cancer
• Radiotherapy = ionising radiation to treat
cancer.
• Gamma rays used as beams to target and kill
cancer cells.
Diagnosis of Cancer
• Gamma rays used
• A tracer solution injected into body that collects in
cancers
• Gamma camera used to detect rays
• Pass through the body so easily detected
Sterilisation of equipment
• To kill microorganisms surgical
instruments need to be sterilised
• Heat usually used but cannot be used
on some things e.g. plastics
• They are irradiated with Gamma rays
instead.
Irradiating food
• Bacteria will cause food to decay or make us ill
• Gamma rays kill bacteria
• Makes food safer and longer lasting
• Does not make food radioactive
• Foods like Fruit, cereals and shellfish are
irradiated.
Smoke Alarms
• Contains a source of alpha particles
• There is an electrical circuit with a gap
between 2 charged plates.
• Air in gap is constantly ionised therefore
constant electric current.
• When smoke get in the alpha particles
are absorbed and stops the current
drops = alarm sounds
Checking thickness
• Use a detector to measure the rate
Beta passes through paper
• Thinner paper = higher beta count.
Tracers in the environment
• Added to water to monitor pollution or
leaking pipes underground
• GM tube follows the pipe to detect leaks.