P7 Physics ‘triple science’ Route map Over the next 24 lessons you will study: Friday 21 October 2011 P7.1 What is a telescope P7.2 Describing lenses P7.3 Refracting telescopes P7.4 Reflecting telescopes P7.5 Radio telescopes P7.7 Images of stars P7.8 The Sun, Moon and Earth P7.9 Observing the skies P7.10 Eclipses P7.11 Star distances P7.12 Star brightness P7.6 Ray diagrams P7.14 Galaxies-cepheid variable stars P7.15 Galaxies one or many P7.13 Star temperatures P7.16 Mapping the Milky Way P7.17 The changing Universe P7.18 Our Sun P7.19 The composition of stars P7.20 Emission spectra P7.21 Atoms and nuclei P7.22 Nuclear fusion P7.23 Behaviour of gases part one P7.24 Behaviour of gases part two P7.25 Types of stars P7.26 Structure of our Sun End of module test P7.27 Protostars P7.28 Star death
P7.21 Atoms and nuclei Decide whether the following statements are true or false:
Understand how scientists have been able to model the structure by using experimental data
Understand how alpha particles scattering enabled Rutherford to understand the nature of the atom and atomic structure.
We will focus on. Friday 21 October 2011 First activity: Write a description of all you know about atoms and the structure of atoms ? (Use the key word if helps you) Literacy: Atom, electron, proton, neutron, nucleus, electron orbital, alpha particle, scattering, radiation, reflection, deflection and atomic structure.. Numeracy: Did you know that atom structure has to be modelled since they are two small to be seen even by electron microscopes. In 12 grams of carbon there are an amazing 6.02 x 10 23 atoms . PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers
Extension questions: 1: What charge do the following subatomic particles have a) proton, b) electron and c) neutron ? 2) Where is most of the mass of an atom found ? 3) Put these in order of their mass (least first) proton, electron and neutron ? 4) Thomson, a scientist that lived just before Rutherford thought that the mass of an atom was even distributed, explain why Rutherford’s experiments proved this theory to be incorrect ? Know this: a: Know the experiments that were done to show the presence of a nucleus b: Know that the way alpha particle are scattered helped Rutherford understand about the sub atomic structure of the atom Friday 21 October 2011 Introduction: The nature of the atom has been studied extensively. The current model we use is that all atoms have a positively charged nucleus containing protons and neutrons and negatively change electrons orbit the atoms nucleus. This model has been used since 1910. Rutherford, using α (alpha) particles (these particles are smaller than atoms), designed experiments to look at what happened when alpha particles were fired at very thin gold foil. They saw that a very small amount of the alpha particles were reflected back, from this they decided that there must be something positively charged within the atom to repel the positively charged alpha particles P7.21 Atoms and nuclei
Look at the photograph and information and answer all the questions: Suggest why electrons were discovered before protons which were discovered before neutrons ? In Rutherford's experiment only one in 8000 alpha particles were back scattered...explain why he need to repeat these observations several times ? The Greeks around 400 B.C first proposed that objects were made from tiny solid atoms sphere like. The plum pudding model of the atom by J. J. Thomson, who discovered the electron, was proposed in 1904 before the discovery of the atomic nucleus. In this model, the atom is composed of electrons surrounded by a soup of positive charge to balance the electrons' negative charges. In 1909, Rutherford having fired alpha particles at gold foil proposed that there must be a positively charged nucleus with electrons orbiting around the atom’s nucleus. Key concepts P7.21 a Greeks: Proposes that all toms are like solid balls so small couldn’t be seen with eyes J.J. Thomson: Proposes after discovering the electrons that the positive charge and mass of atom is evenly distributed E. Rutherford: Proposes after firing alpha particles at gold foil that the charge and mass of the atom is found in centre. Ideas about atoms over time
Look at the photograph and information and answer all the questions: Rutherford repeated and checked his experiments many times before he published his findings. Why was this an important thing to do ? Why is the statement ‘firing a gun at a tissue and finding some of the bullet bouncing back a good analogy of what this experiment showed ? Rutherford performed an experiment where he fired alpha particles at thin gold foil. Detectors were positioned at every angle to find how the alpha particles were scattered by the gold atoms. It was discovered that some alpha particles (one in 8000) were reflected back to the source – rather like firing a gun at tissue paper and finding some of the bullets bouncing back. He proposed that each atom had a tiny core or nucleus with a mass and a positive charge. This charge repelled the alpha particles. Most particles are undeflected Rutherford's experiment Rutherford's experiment Key concepts P7.21 b Alpha particles Gold atoms
Look at the photograph and information and answer all the questions: How do we know form Rutherford’s experiment that an atom’s nucleus is very tiny ? When taking about the properties of solid liquid and gases explain why the Greek model is correct ? The atom is a basic unit of matter that consists of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons (except hydrogen, which is made form only a proton and neutron. The electrons of an atom are bound to the nucleus by the electromagnetic force. Key concepts P7.21 c Greeks: Proposes that all atoms are like solid balls so small they couldn’t be seen with using eyesight Thomson: Proposes after discovering the electrons that the positive charge and mass of atom is evenly distributed Rutherford: Proposes after firing alpha particles at gold foil that the charge and mass of the atom is found in centre. Ideas about atoms over time
P7.21 Plenary Lesson summary: alpha repelled positively experiments Friday 21 October 2011 The 1904 Thomson model was disproved by the 1909 gold foil experiment, which was interpreted by Ernest Rutherford in 1911 to imply a very small nucleus of the atom containing a very high positive charge (in the case of gold, enough to balance about 100 electrons), thus leading to the Rutherford model of the atom. How Science Works: Research into nuclear fusion and how energy is released during the fusion of two simple atoms Preparing for the next lesson: The _________ carried out by Rutherford and his team proved that there are _____ charged nucleons in the nucleus. These charged protons ________ a small amount of the ______ radiation beam, which is also positively charged. Decide whether the following statements are true or false : False True 3: Only 1 in 8000 alpha particles was back-scattered? False True 2: they used a alpha beam of radiation? False True 1: the metal used in Rutherford's experiments was platinum?
P7.22 Nuclear fusion Decide whether the following statements are true or false:
Understand the differences between processes of fusion and fission
Understand the attractive and repulsive forces between nuclear particles
We will focus on. Friday 21 October 2011 First activity: Write down and describe all that you know about the sub atomic structure of an atom Literacy: Atom, sub atomic structure, neutrons, electrons protons, orbits, nuclear fusion, nuclear fission, nuclear forces, attraction, repulsion and energy Numeracy: The Sun fuses hydrogen atoms together at the rate of a staggering 700 million tonnes of hydrogen every second. At this rate the Sun’s hydrogen reserves will last a further 4.5 billion years. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers
Extension questions: 1: How many protons and neutrons are there in a hydrogen atom ? 2: What is the charge on a) an electron b) a neutron c) a proton ? 3: Draw an electron configuration diagram for lithium given that lithium has 3 protons, 3 electrons and 4 neutrons ? 4: Define the terms fusion and fission ? 5: What are the starting materials and products for a) nuclear fusion and b) nuclear fission ? Know this: a: Know the difference between fusion and fission. b: Know the attractive and repulsive forces acting in the nucleus. Friday 21 October 2011 Introduction: In the process of nuclear fusion (the process going on in stars) two hydrogen atoms join together to form helium releasing large quantities of energy. The reason why the protons in hydrogen can join together is because there are strong nuclear forces in a nucleus so that the positively charged protons can be near without repelling each other. This force has a very short range and only acts when two protons are very close together. In nuclear fission , (the process used in nuclear power stations) a large nucleus (normally an unstable isotope) splits releasing large quantities of energy and few neutrons whilst forming medium sized nuclei) . P7.22 Nuclear fusion
Look at the photograph and information and answer all the questions: What new element is made from the fusion of 2 hydrogen atoms ? In the last 4.5 billion years the sun has consumed 50 % of its hydrogen, how much long can the sun last if it uses hydrogen at the same amount ? Nuclear fusion is the process in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy. In the simplest case of hydrogen isotope fusion, helium is produced when tritium and deuterium are fused. Nuclear fusion occurs naturally in all active stars Key concepts P7.22 a Nuclear fusion of hydrogen
Look at the photograph and information and answer all the questions: Name three types of radiation emitted by the Sun ? Although all electromagnetic waves travel through space from the Sun to Earth’s surface, sound doesn’t. Explain why this is a good thing ? The sun fuses hydrogen atoms forming helium and releasing vast quantities of energy. Each second of every day our Sun converts about 700 million tons of hydrogen into about 695 tons of helium. The missing 5 million tons is converted into energy equivalent to the detonation of about 100 billion one-megaton bombs, two hundred million times the explosive yield of every nuclear weapon ever detonated on Earth. Key concepts P7.22 b Nuclear fusion inside the Sun
Key concepts Look at the photograph and information and answer all the questions: Nuclear fission is when a large nucleus like Urnaiun 235 an unstable radioactive element splits forming two medium sized nuclei. The diagram shows an atom of Uranium gains a neutron then this large molecule splits forming two medium sized molecules of krypton and barium, this process also releases 3 neutron at the end. This process of fission releases energy, typically 200 MeV. Explain using diagrams and words the difference between fusion and fission ? What are the products of the nucleus splitting in nuclear fusion ? P7.22 c Nuclear fission
Key concepts Look at the photograph and information and answer all the questions: In a chain reaction, how does more and more fissions of unstable occur ? Calculate the number of fission after just four generations (the diagram shows three generations) ? A chain reaction refers to a process in which neutrons released in fission produce an additional fission in at least one further nucleus. This nucleus in turn produces neutrons, and the process repeats. The process may be controlled (nuclear power) or uncontrolled (nuclear weapons). If each neutron releases two more neutrons, then the number of fissions doubles each generation. In that case, in 10 generations there are 1,024 fissions and in 80 generations about 6 x 10 23 fissions. Fission of Uranium 235 as a chain reaction P7.22 d
. P7.22 Plenary Lesson summary: fuels energy power hydrogen Friday 21 October 2011 The fusion of hydrogen in the sun's core is alchemy on a grand scale in the sense that one element is turned into another, where hydrogen turns into helium. Hydrogen fusion has been going on in the sun for about 5 billion years and calculations show that there is enough hydrogen left to keep the sun going for about the same length of time into the future. How Science Works: Research into how gases behave, how to describe a gas and how gases behave when volume and pressure is changed. Preparing for the next lesson: The Nuclear fusion process ______ the sun. Two _______ nuclei fuse together to form a new helium atom. This fusion process releases _________. When a large nuclei splits into two medium sized nuclei this is called nuclear fission, this is the process used in nuclear ________ stations Decide whether the following statements are true or false : False True 3: Electrons and protons are present in the nucleus ? False True 2: Fission is the joining up of two large nuclei ? False True 1: Fusion is the joining up of two small nuclei releasing energy ?
P7.23 Behaviour of gases Decide whether the following statements are true or false:
Understand the relationship between pressure and volume of a typical gas
Understand the definitions of pressure and volume
Understand how to convert between temperature and pressure scales
We will focus on. Friday 21 October 2011 First activity: Explain how increasing pressure inside a gas can change its properties ? Literacy: Gas, volume, pressure, gas particles, density, flow, squashing, mass, pressure, kinetic model, temperature, Celsius and Kelvin. Numeracy: Blood pressure is approximately 0.01 bar, this is very small but sufficient to push your blood around your circulatory system. Atmospheric pressure is 1 bar and the pressure inside an average car tyre pressure is approximately 2.1 to 2.5 bar. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers
Extension questions: 1: Describe the properties of a typical gas ? 2: Sketch a graph showing how volume and pressure are related ? 3: Explain clearly why reducing the volume would increase the pressure ? 4: Explain how the pressure of a gas changes in a syringe as you compress the gas inside the syringe ? 5: When a bike tyre is being pumped up what is happening to the a) the volume of the gas and b) the pressure of the gas ? Know this: a: Know how pressure and volume are related in a typical gas. b: Know the definitions of temperature volume and pressure and the units Friday 21 October 2011 Introduction: The sun is made up hydrogen and helium, both are gases. To understand how nuclear fusion function and stars generate huge amounts of energy we must first understand how gases behave when they become hot or the pressure Pressure is the force a gas exerts per unit area on the walls of the container. Volume is the amount of space the gas occupies. Temperature is how hot the gas is In gases as the volume increases the pressure decreases, equally as the volume decreases the pressure increase. P7.23 Behaviour of gases
Key concepts P7.23 a Look at the photograph and information and answer all the questions: The connection between pressure and the volume of a gas relies on the kinetic model of matter. Gas particles move about freely and at 25 o C they move with speeds of up to 450 m/s. As they move around at these speeds they bump into the walls of their container. Billions of these collisions happen every second. These collisions, their speed and frequency make up gas pressure . Look at the two diagram above showing the gas particles in the two syringes, describe what happens as you reduce the volume in the syringe ? Explain why you can easily squash or compress gases but not liquids or solids ? Pressure (Pascals ( N/m 2 ) Volume (m 3 ) 1 atmosphere 2 atmospheres 100 75 50 25 0 0 1 2 3 4 Modelling pressure and volume changes in gases
Look at the photograph and information and answer all the questions: Air in the atmosphere is made up of a number of gases. These gases press down on the Earth’s surface, exerting a force that we call atmospheric pressure. Although we are usually unaware of this pressure, it actually presses down very hard – roughly equivalent to the force of an elephant balancing on a desk ! Name three gases that are found in air ? Explain the movement of particles in a gas and how does this movement change if you heat the gas particles ? As you climb vertically from sea level to high altitude, what happens to atmospheric pressure ? P7.23 b Key concepts
Key concepts P7.23 c Look at the photograph and information and answer all the questions: As you compress a gas into smaller and smaller volumes, the billions of collisions with the walls of its contain increase. This increase the pressure of the gas. In fact for any gas, at a constant temperature the volume is inversely proportional to its pressure. When you double the volume you halve the pressure of the gas, when you halve the volume you double its pressure. Look at the graph (above left) explain the relationship between pressure and volume in a typical gas ? Use the graph to work out what the volume would be if the pressure of the gas rose form 3900 to 600 Pascal's (N/m 2 ) ? Pressure (Pascals ( N/m 2 ) 20 15 10 5 0 0 100 150 200 300 400 500 600 700 Volume (m 3 ) Modelling pressure and volume changes in gases
Look at the photograph and information and answer all the questions: Unlike gases, particles in a liquid are touching. This means that unlike a gas, you cannot squash a liquid. A liquid like oil or water can be used to transmit pressure from one place to another. This is how hydraulics work. Braking systems found in both cars and mountain bikes use hydraulics. Also by changing the area of the both pistons, a small force can produce a large force. Explain why brakes go soft or spongy when air bubbles gets into the brake fluid ? Explain why it is harder to stop water coming from a tap when compared to air coming out of a bicycle pump ? Give three different uses for hydraulics ? Pressure in gases Force 3 N Area 3 cm 2 Syringe 1 Syringe 2 Force 6 N Area 6 cm 2 Pressure = 1 N/cm 2 Small force Large force P7.23 d Key concepts
P7.23 Plenary Lesson summary: space force increases helium Friday 21 October 2011 Boyle's law describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system. The law was named after chemist and physicist Robert Boyle, who published the original law in 1662. The law itself can be stated as follows: How Science Works: Research into the link between pressure and temperature in a gas and how increasing or decreasing temperature influences the pressure inside a gas. Preparing for the next lesson: Pressure is the ______ exerted by the walls of a container. Volume is the amount of _____ a gas occupies. As the pressure __________the volume decreases. The two gases in the suns atmosphere are hydrogen and ________. Decide whether the following statements are true or false : False True 3: As pressure increases, the gas particles exert a greater force on the container ? False True 2: In a gas, pressure increases when the volume increases ? False True 1: Units of volume can be m 4 ?
P7.24 Behaviour of gases part two Decide whether the following statements are true or false:
Understand the relationship between temperature, volume and pressure.
Understand how to convert between the different temperature scales.
We will focus on. Friday 21 October 2011 First activity: Predict what will happen to the temperature of a gas if a) the pressure increases inside a gas and b) the volume decreases inside the gas ? Numeracy: Did you know there is no limit to positive temperatures but there is a limit to how cold you can go. At -273.3 o C, all matter stops vibrating. Therefore temperature can go no lower. Scientist have so far come with 0.1 o C or absolute zero PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers Literacy: Gas, volume, pressure, gas particles, density, flow, squashing, mass, pressure, kinetic model, temperature, Celsius and Kelvin.
Extension questions: 1: What would happen to the volume of air in a balloon if a) the temperature dropped and b) the temperature increased ? 2: What would happen to the temperature inside a container if the a) the pressure increased and b) the pressure decreased ? 3: Know what you know about pressure and temperature why should you a) never put food tins into an oven and b) always check your tyre pressure in the winter months ? Know this: a: Know how to convert between the Kelvin and the Celsius temperature scales. b: Know how to clearly explain and use examples to show the relationship between temperature, volume and pressure. Friday 21 October 2011 Introduction: Experiments carried out to look at the relationship between temperature, pressure and volume need to be carefully designed. One of the variables needs to be kept the same so the other two variables can be analyzed. Of the remaining two variables one needs to be controlled whilst the other one is changed. Temperature can be measured using several units Celsius, Kelvin and Fahrenheit. Kelvin and Celsius are used in science. At absolute zero or 0 o K the temperature in Celsius is -273 °C. At 0 °C the temperature in Kelvin is 273 o K P7.24 Behaviour of gases 2
Key concepts P7.24 a Look at the photograph and information and answer all the questions: Charles's Law, or the law of volumes, was found in 1787. It says that, for an ideal gas at constant pressure, the volume is proportional to the absolute temperature. This can be found using the kinetic theory of gases or a heated container with a variable volume (e.g. flask with a balloon). Using this equipment we find that the volume of a gas is proportional to the temperature of that gas in Kelvin Look at the graph (above left) explain the relationship between temperature in Kelvin and volume in a typical gas ? Use the graph to work out what the volume (m 3 ) would be if the temperature of the gas decreased from 200 to 100 Kelvin Temperature K 25 20 15 10 0 0 100 200 273 373 400 473 573 673 Volume (m 3 ) Modelling pressure and volume changes in gases - 273 -173 -73 0 100 200 300 400 Temperature o C
Key concepts Look at the photograph and information and answer all the questions: The Kelvin scale (K) was developed by Lord Kelvin. The zero point of this scale is equivalent to -273.15 °C on the Celsius scale. This zero point is considered the lowest possible temperature of anything in the universe. Therefore, the Kelvin scale is also known as the "absolute temperature scale". At the freezing point of water, the temperature of the Kelvin scale reads 273 K. At the boiling point of water, it reads 373 K. Convert these temperatures from celcius to Kelvin a) 100 o C b) -4 o C c) 45 o C d) 37 o C ? Convert these temperatures from Kelvin to Celsius a) 100K b) 0K c) 273K and d) 373K ? Convert these temperatures from celcius to Kelvin a) 100 o C b) -4 o C c) 45 o C d) 37 o C ? P7.24 b The Kelvin and Celsius scale
Key concepts P7.24 c Look at the photograph and information and answer all the questions: Whereas the Kelvin scale is widely used by scientists, the Celsius or Fahrenheit scales are used in daily life. These two scales are easier to understand than the large numbers of the Kelvin scale. Could you imagine waking up to your radio and hearing the DJ tell you that "It's going to be a beautiful day today with sunny skies and a balmy temperature of 297 K!" That's 24 °C or 75 °F Looking at the temperatures given in both Celsius and Kelvin can you understand why every day pole do not use the Kelvin temperature scale ? Convert the following temperatures in Kelvin back to the Celsius temperature scale a) 132.2 K b) 0 K c) 456.2 K ? Using both Kelvin and Celsius for temperature Celsius O o C 100 o C 37.4 o C Kelvin 273 K 373 K 400.4 K melting ice water boiling human body temp
Key concepts P7.24 d Look at the photograph and information and answer all the questions: Explain why the air displaces the water from the beaker as the gas is heated inside the test tube ? If the heated air didn’t rush into the beaker displacing the water what would happen to the pressure inside the test tube as the air is heated ? The diagram above shows how a sample of air would behave if it were heated. Its only heated a small amount as shown by the diagram and so the gas would increase in volume so that the pressure in the test tube would increase, this would then force the air out of the test tube and into the collection beaker. The more you heat the sample of gas the higher the pressure and the more air would be displaced into the collection beaker. Volume (m 3 ) Modelling pressure and volume changes in gases Temperature o K
P7.24 Plenary Lesson summary: Decreases increases volume Kelvin Friday 21 October 2011 In February 2003, the Boomerang Nebula was observed to have been releasing gases at a speed of 500,000 km/h (over 300,000 mph) for the last 1,500 years. This has cooled it down to approximately 1 K, as deduced by astronomical observation. This is the lowest natural temperature ever recorded in any part of the known Universe !!! How Science Works: Research into the life cycle on an average star and how stars different form one another. Look into the Herztsprung-Russell diagram of stars Preparing for the next lesson: At a fixed _______ the temperature _________ as the pressure decreases. at a fixed pressure the volume increases as the as the temperature _________. To convert from celcius to Kelvin add 273, to convert from _______ to celcius subtract 273. Decide whether the following statements are true or false : False True 3: In order to convert from °C to K just add 273 ? False True 2: Pressure in gases can be measured in °C or K ? False True 1: There is a linear relationship between temperature and pressure of a gas ?
P7.25 Types of stars Decide whether the following statements are true or false:
Understand how to map stars on to the Hertzsprung-Russell diagram
Understand that 90% of al stars fall into the main sequence category
We will focus on. Friday 21 October 2011 Literacy: Luminosity, brightness, distance, energy, structure, core, radioactive zone, photosphere, nuclear fission, corona, nuclear fusion and light. Numeracy: There are 3 mains groups of stars. 90% of all stars are known as stars with the main sequence, this groups also includes our own star, the sun. 10% are white dwarfs small and hot and about 1% are red giants, bright but not very hot. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers First activity: Write how the surface temperature of a star relates to a) is mass and b) its luminosity ?
Extension questions: 1: Give the link between the colour of a star and its surface temperature if their distance from Earth were the same ? 2: What temperature would a) a red star b) violet star be? 3: What's the definition of luminosity and how is it calculated ? 4: What is a) a white dwarf star and b) What is a supergiant star ? 5: How do we know that most stars spend most of their time in the main sequence ? Know this: a: Know how to map stars using the Hertzsprung-Russell diagram b: Know that 90% of all stars fall into the main sequence category Friday 21 October 2011 Introduction: It was known by the start of the 20 th century that stars are different colours, perhaps because their different distances from Earth or their different surface temperatures, for example red stars are cool and blue stars are hot. Knowing the distance of a star from Earth means that its luminosity can be calculated. A chart, called the Hertzsprung-Russell diagram, shows the link between luminosity (brightness) verses temperature. With over 200,000 stars surveyed by 1924 Hertsprung-Russell concluded that 90% of all stars fell into a group called the main sequence, 10% were white dwarfs, small and hot and less than 1% were red giants, bright but not. P7.25 Types of stars
Key concepts P7.25 a Look at the photograph and information and answer all the questions: In the Hertzsprung-Russell (HR) diagram, each star is represented by a dot. The position of each dot on the diagram tells us two things about each star: its luminosity (or absolute magnitude) and its temperature. The vertical axis represents the star’s luminosity or absolute magnitude,but you can think of it as how bright or how dim the star appears. The horizontal axis represents the star’s surface temperature (not the star’s core temperature –Usually this is labeled using the Kelvin temperature scale. What temperature in Kelvin and brightness will a) super giant b) white dwarf be ? What variation can be seem in the main sequence stars ?
Look at the photograph and information and answer all the questions: The Hertzsprung-Russell diagram shows luminosity plotted against surface temperatures of stars. This temperature determines colour, with red stars at under 3000 deg, moving higher through orange, yellow, white, and blue, and ending at violet for stars at over 30,000 deg. The majority of stars were found to fall on a diagonal line, called the 'Main Sequence, like our sun with a life cycle of around 8 to 10 billion years. The closest star to our Sun, Proxima Centauri, is a red star with a mass and a radius each one-tenth of the Sun's, and a life cyle of 1000 billion years. At the other end of the scale, the star Beta Centauri emits blue-violet light, is about 15 times the Sun's mass, 10 times its radius, and has a life cycle of 8 million years. Explain why smaller stars by mass or radius have a) a cooler surface temperature and b) a longer life cycle than our own Sun ? Key concepts Using the Herztsprung-Russell diagram P7.25 b Explain why larger stars by mass or radius have a) a hotter surface temperature and b) a shorter life cycle than our own Sun ?
P7.25 Plenary Lesson summary: group main sun brightness Friday 21 October 2011 So how do you read the HR diagram?. A star in the upper left corner of the diagram would be hot and bright. A star in the upper right corner of the diagram would be cool and bright. The Sun rests approximately in the middle of the diagram, and it is the star which we use for comparison. A star in the lower left corner of the diagram would be hot and dim. A star in the lower right corner of the diagram would be cold and dim. How Science Works: Research into the structure and anatomy of main sequence stars like our own star, the Sun Preparing for the next lesson: Stars can be grouped according to their ________ and temperature, as seen on the Hertzsprung-Russell diagram. Most stars in fact about 90% of all stars belong to a ______ called the ______ sequence. The ______ is approximately in the middle of its life cycle and hence main sequence. Decide whether the following statements are true or false : False True 3: Our Sun is expected to last about 9 to 10 billion years ? False True 2: Larger stars (by mass) have shorter life cycles compared to our Sun ? False True 1: Red giants are cool bright stars found in the top right corner of H-R diagram ?
P7.26 Structure of our Sun Decide whether the following statements are true or false:
Understand that our own star, the Sun is a main sequence star.
Understand about the structure of the Sun and how heat and light are produce by nuclear fission
We will focus on. Friday 21 October 2011 Literacy: Star, Sun, Solar system, luminosity, brightness, distance, energy, structure, core, radioactive zone, photosphere, nuclear fission, corona, nuclear fusion and light. Numeracy: Our sun is approximately half way through its 9 billion year life cycle. The Sun’s diameter is about 870,000 miles wide. The Sun is 109 times wider than Earth, and is 333,000 times heavier. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers First activity: Write down what types of electromagnetic waves the Sun produces, how they reach Earth and how are they produced ?
Extension questions: 1: What fuel drive nuclear fission inside the Sun’s core ? 2: A star light he sun has a life cycle of about 9 to 10 billion years. It produces constant light and temperature. What does this tell you about the position of the sun o the H-R diagram 3: Which two elements are found in the Sun ? 4: Compare the Sun’s core and surface temperature ? 5: Whys can we see the results of nuclear fission but not hear the results of nuclear fission ? Know this: a : Know that our own star, the Sun is a main sequence star. b: Know about the structure of the Sun and how heat and light are produce by nuclear fission Friday 21 October 2011 Introduction: The Sun's mass is 2 x 10 27 tonnes. About 75% of the Sun is hydrogen, the rest is mostly helium. The surface of the sun is called the photosphere and is made up of thick gases. The photosphere has a surface temperature of about 5,500 to 6000 o C and comprises of two layers of atmosphere called the chromosphere and the corona , which is the outermost layer of the sun and stretches towards the planets as far as Mercury, getting thinner all the time. The interior, made up of three hot layers. The core is the hottest, around 4 to 15,000,000 °C. This is where the light we see is created by nuclear reactions between hydrogen and helium. In the next layer up, the radiative zone , the heat created in the core moves outward through the gases. In the final layer, convective zone , energy is transported by convection (like boiling soup). Convection therefore allows the photosphere to be heated up by the interior so that we can see the light from the sun . P7.23 Structure of our Sun
Key concepts P7.26 a Look at the photograph and information and answer all the questions: The Sun is the star at the centre of the Solar System. It has a diameter of about 1,392,000 km, about 109 times that of Earth, and its mass is 330,000 times that of Earth. About three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. Less than 2% consists of heavier elements, including oxygen, carbon and neon. What element is the Sun made from and how could prove your answer ? Is our Sun a a) red dwarf, b) white dwarf or c) a main sequence star on the H-R diagram ? The Sun’s surface
Key concepts P7.26 b Look at the photograph and information and answer all the questions: Name three types of radiation emitted by the Sun ? The sun is made up of several layers. The centre of the sun, the Core, is the only part of the sun that actually makes energy. The temperature in the Core is about 15,000,000 o C. The next layer of the sun is the radioactive Zone, the temperature here is about 5,000,000 o C. The next section of the sun is called the Photosphere, which is actually what you see when you look at the sun, is made form two parts and has a surface temperature of about 5,500 to 6000 o C.. Explain why the temperature cools as you move from the Sun’s core to the Sun’s surface ? Inside the Sun
P7.26 Plenary Lesson summary: predictions data three 5,500 Friday 21 October 2011 The Sun's mass is 2 x 10 27 tonnes About 75% of the Sun is hydrogen, the rest is mostly helium. Gravity holds the Sun together. The weight of the outer layers of the Sun causes the density and temperature to increase inwards, until at the centre the temperature is 15 million degrees Celsius and the density is 160 times that of water. How Science Works: Research into the structure and anatomy of main sequence stars like our own star, the Sun Preparing for the next lesson: The structure of the sun has been elucidated by using ______ from the SOHO satellite and making ________ based on the data returned. The sun has _____ parts to its structure with the outermost part, the photosphere being the coolest which has an average surface temperature of about ________ o C. Decide whether the following statements are true or false : False True 3: The sun is an average star in the main sequence of stars ? False True 2: Nuclear fusion reactions occur in the photosphere ? False True 1: The hottest part of the sun is the core which is about 13 to 14 million K ?
P7.27 Protostars Decide whether the following statements are true or false:
Understand how stars like our Sun and planetary systems like our Solar system have formed.
Understand what a protostar is and why they are important
We will focus on. Friday 21 October 2011 First activity: List the stages of how a new star forms ? Literacy: Protostar, dust, dust cloud, contraction, rotation, temperature, heating up, nuclear fusion, hydrogen, gravity, compression, star disc and star Numeracy: The time taken for a star to form ( known as a the proto-star phase) from contracting gas is though to take between 100,000 to 1 million years. At the same time as a star forms debris trapped by its huge gravity, also forms planets like our own ! PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers
Extension questions: 1: List the type of materials that stars for from ? 2: Describer the very early stages of star formation and what is the main force involved ?what temperature is required for the nuclear fusion process to start ? 3: In the middle stages of star formation what happens to the gases at the core of the protostar ? 4: At what point is a star said to be ‘born’ 5: How long was the sun a protostar for ? Know this: a: Know how stars like our Sun and planetary systems like our Solar system have formed. b: Know what a protostar is and why they are important Friday 21 October 2011
The raw material of stars is huge clouds of hydrogen gas Over a period of time many steps take place to enable a new star to form.
Initially a cloud of dust is pulled together by gravity forming a hot swirling disc.
The centre of which gets hotter and hotter as the disc gets smaller and smaller.
When the temperature gets hot enough fusion reactions start to take place and a new star is born.
Dust in the furthest edges of the disc also start to clump together and this creates a new planets or planet orbiting the star. In the early stages the newly forming star is called a protostar.
Key concepts P7.27 a Look at the photograph and information and answer all the questions: Look at the picture above what forces are in action as the core pf the developing star begins to become denser and hotter ? Stars begin their lives as clouds of dust and gas called nebulae. . Matter in the gas cloud will begin to coalesce into a dense region called a protostar. As the protostar continues to condense, it heats up. Eventually, it reaches a critical mass and nuclear fusion begins. This begins the main sequence phase of the star. Above is a coloured picture and other images, showing the formation of a star with the core beginning to increase in both temperature and mass Explain why it is useful to take pictures of the same protostar using x rays, UV and Infra red ? Light Hubble Telescope The birth of a star (protostar)
Key concepts P7.27 b Look at the photograph and information and answer all the questions: Explain why the most common element found in the Eagle nebula is hydrogen gas which is the building material for all stars ? Explain why larger or brighter stars often only last a few million years when compared to an average star like our own sun ? Billions of stars, found in millions of galaxies, filling billions of light years of space, but how are galaxies and stars formed. In 1998, the Hubble telescope and one of its many images, finally gave us spectacular evidence that tells scientists how stars and galaxies are formed. The Eagle nebula (pictured below) is a cloud of hydrogen and dust millions of light years across. At the end of each finger like protrusion, the gravitational forces form a ball of hydrogen. Huge gravitational forces superheat the hydrogen so that nuclear fusion begins, light is produced and a star is born. The Eagle nebula
P7.27 Plenary Lesson summary: gravity hotter new Kinetic Friday 21 October 2011 The life span of a star depends on its size. Very large, massive stars burn their fuel much faster than smaller stars. Their main sequence may last only a few hundred thousand years. Smaller stars will live on for billions of years because they burn their fuel much more slowly How Science Works: Research into the life cycle of an average star and what happens to a star after hydrogen gas is exhausted as a fuel Preparing for the next lesson: Protostars are the intermediate stage in the development of a ___ star. They are a mass of swirling dust and gas that’s shrinking and getting ______ and hotter. The temperature increases due to the forces of ______ and the energy transformation from gravitational potential energy to ______ energy. Decide whether the following statements are true or false : False True 3: Often 4 shockwaves are seen at the exact moment a star forms ? False True 2: New stars and planetary systems are usually elliptical ? False True 1: It can take up to 1 million years for a protostar to form a new star ?
P7.28 Star death Decide whether the following statements are true or false:
Understand what happens when the fusion process ends and a star exhaust its supply of hydrogen fuel
Understand what happens from protostar to neutron star or even a black hole
We will focus on. Friday 21 October 2011 First activity: Write down everything you know about star death ? Numeracy: Across the whole Universe there are many billions of Glaxies contains billions of stars. It is estimated that each day an amazing 275 million of stars end their life cycle, expanding forming a red giant and then ceasing to produce any light at all. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers Literacy: Protostar, dust, dust cloud, contraction, rotation, temperature, nuclear fusion, hydrogen, gravity, compression, supernova, red giant, balck hole, nebula, white dwarf, neutron star and pulsar.
1: Explay what triggers the death of a star like our own Sun ?
2: Draw a flow diagram to show the steps in the death of a
A small star like the sun
A large star like Beta Centuari ?
3: What's the difference between a red giant and a supergiant ?
4: Explain what happens to the layers of a star when the nuclear fusion process slows down ?
Know this: a: Know what happens when the fusion process ends and a star exhaust its supply of hydrogen fuel b: Know what happens from protostar to neutron star or even a black hole. Friday 21 October 2011 Introduction: A star only has a set amount of hydrogen fuel, once this is used up in the nuclear radius of a star will determine it’s the length of its life cycle. Most star lasts for between 8 to 10 billion years. Smaller red stars can last up to 1000 billion years and super hot white dwarf can consumer their fuel in less than 5 million years. The size by mass of the star will also determine the product of star death: If the star is relatively small like the sun it becomes a red giant and then forms planetray nebula before forming a white dwarf If the star is large then it becomes a super giant. The supergiant will then change into a supernova which in turn becomes either a neutron star or a black hole. A supernova explosion occurs when a supergiant become so big it can not be held together by the pressure of the core and the supergiant collapses inwards. Supernovas occur only once a century in each galaxy. P7.28 Star death
Key concepts P7.28 a Look at the photograph and information and answer all the questions: Scientists believe that in the early Universe only hydrogen existed. Explain how other elements have formed ? Explain why and how all life will eventually end here on planet Earth ? The Sun has a lifespan of about 9 billion years and is already halfway through its life using up to 300,000 tonnes of hydrogen gas every second. Eventually, when all the hydrogen and helium is consumed, the Sun will rapidly expand forming a red giant that engulfs and scorches the first four planets including Earth. What follows then is its contraction, the formation of a white dwarf and then a neutron star. During this phase heavier elements are formed. The life cycle of an average star like our sun Stellar nebula Average star Red Giant Planetary nebula White Dwarf Neutron star 4.5 billion years B.C 4.5 billion years A.D 4.6 billion years A.D
Key concepts P7.28 b Look at the photograph and information and answer all the questions: Does a large star have a longer or shorter life cycle when compared to our own star the Sun ? If the star is massive enough, the collapse will trigger a violent explosion called a supernova. Stars at least 1.4 times larger than the Sun will collapse further to become a neutron star. The matter inside the star will be compressed so tightly that its atoms are compacted into a dense shell of neutrons. If the remaining mass of the star is more than about 3 to 4 times that of the Sun, it will collapse so completely that it will literally disappear from the universe. What is left behind is an intense region of gravity called a black hole. What possible fate awaits a large star after it becomes a type II supernova (there are three answers ? The life cycle of an large star
Key concepts P7.28 c Look at the photograph and information and answer all the questions: Is the expression ‘we are all made from star dust’ largely correct or false ? The nebula that is expelled from the large star may continue to expand for millions of years and is called a supernova. Eventually, the gravity of a passing star or the shock wave from a nearby supernova may cause it to contract, starting the entire star formation process all over again. This process repeats itself throughout the universe in an endless cycle. It is this cycle of stellar evolution that produces all of the heavy elements required for life. Our solar system formed from such a second or third generation nebula. What are the main differences between a neutron star and a black hole ? Supernova and beyond Light image of supernova Hubble Telescope
Look at the photograph and information and answer all the questions: Why did Ptolemy and his peers in 140 AD think that the Earth was at the centre of the Universe ? Hubble's observation that the Milky Way was just one of many millions of galaxies was an important discovery…explain why ? Humans, for thousands of years have asked questions about their own history, the history of the solar system and Universe. Early philosophers and modern scientists have given us different answers to the one single question: How and when did the Universe begin ? Over the last two thousand years, many different theories have been offered by scientists to explain what events began, that led to the formation of the Universe and all the galaxies that we observe today . Ptolemy: Proposes in 140 AD that the Earth is a sphere and is at the very centre of the Universe. Copernicus: Proposes in 1600 AD that the Sun is the very centre of the Universe, with the Earth orbiting it. Hubble: Proposes that our galaxy, the Milky Way is just one of billions of similar Galaxies. Hawkins: Popularised that the Universe started with a big bang around 14 billion years ago and is still in constant expansion. Key concepts P7.28 d
Key concepts P7.28 e Look at the photograph and information and answer all the questions: Explain why not even light can escape from a black hole ? Black holes are called the vacuum cleaners of the Universe and are the collapsed remains of stars. When a failed star implodes on itself, the mass becomes super concentrated. The gravitational forces are so huge that not even light can escape. That why it appears black. There are numerous black holes which can consume other stars or planets when they pass near by. The picture above shows the hydrogen gas of an average star being pulled into the black hole. Scientists do not know whether the Milky Way contains a black hole Explain how a black hole forms from supernova ? Black holes Image of a black hole (digital)
P7.28 Plenary Lesson summary: supergiant neutron Fusion Hydrogen Friday 21 October 2011 Very heavy stars will continue to fuse heavy elements in order to produce more energy. However, once iron is formed, it cannot be fused to make more energy since it has such a high binding energy and is therefore very stable. The core will collapse under gravity and huge amounts of gas on the surface of the star will explode out. This star is now called a supernova. How Science Works: Revise for an end of module test Preparing for the next lesson: Stars start dying when the run out of _________ as this means the nuclear ______ reactions stop. Depending on the original size of the star either a red giant or a super red star is then formed. The _________ then undergo a supernova explosions and become either black holes or ______ stars depending on their core mass. . Decide whether the following statements are true or false : False True 3: giant reds are hotter than the initial star ? False True 2: the temperatures reacted during a supernova at 10 billion K ? False True 1: Black holes and neutron stars are very dense ?