Discovering em spectrum
•Download as DOCX, PDF•
0 likes•69 views
This document discusses how different types of electromagnetic radiation are detected and used in astronomy. It provides links to videos and websites about radio waves, microwaves, infrared waves, ultraviolet light, x-rays, and gamma rays. Students are instructed to view the videos and websites to learn about the discovery of each type of radiation, how telescopes and detectors observe them, and what can be seen in space using each wavelength. Questions are provided for students to answer to help them understand the material.
Report
Share
Report
Share
Recommended
08 Feb 17 Light, Electron E Levels Actual Presented
Introduction to electromagnetic radiation and light. Viewing atomic spectra with diffraction gratings. Optical tweezers (cool example of light having momentum).
Ultra violet light
Ultraviolet radiation is an electromagnetic wavelength between 10-400 nanometers that can cause sunburn and skin cancer if exposed to for long periods without protection. It is used in astronomy to observe hot objects in space, as UV radiation is emitted. On Earth, UV light is used in fluorescent lamps, lasers, and for security features like watermarks on credit cards that are only visible under UV light. Prolonged exposure can damage DNA and increase risk of the skin cancer malignant melanoma.
Emily p
The document discusses the electromagnetic spectrum, which consists of radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. Each type of electromagnetic wave has a different wavelength and frequency, with radio waves having the longest wavelengths and lowest frequencies, and gamma rays having the shortest wavelengths and highest frequencies. Examples are given for how each type of electromagnetic wave is used, such as radios using radio waves, cell towers transmitting microwaves, heat lamps emitting infrared waves, stars emitting visible light, black lights using ultraviolet waves, X-rays being used to see broken bones, and neutron stars emitting gamma rays.
prueba
The document discusses the development of a Littrow spectrograph and its advantages over a classical spectrograph. It describes using the Littrow configuration to enable amateur astronomers to conduct research through spectroscopy. Details are provided on constructing the spectrograph, aligning it, and obtaining spectra of various astronomical objects using a DSLR camera mounted to a telescope.
Chapter 03 Tests
The document is a series of questions and answers about modern telescopes and astronomy. It discusses how modern telescopes use mirrors rather than lenses, how "seeing" refers to the quality of images affected by atmospheric conditions, and how different types of telescopes like the Hubble Space Telescope are useful for observing different wavelengths of light and regions of space.
Multiwavelength astronomy
Here's my presentation on "Multiwavelength Astronomy".I had presented it on National Astronomy Olympiad-2016,Nepal.
Light intensity/electromagnetic Waves/Wave-quantum Theory/Radioactivity
Brief introduction on
Light intensity quality,
Invisible spectrum,
EM radiation-properties,
Theory of wave and quanta
Radio-activity
Radio-activity/substances
Radio-activity: substances, law, curve, half life, decay factor etc.
Details about radium, cobalt, cesium
Recommended
08 Feb 17 Light, Electron E Levels Actual Presented
Introduction to electromagnetic radiation and light. Viewing atomic spectra with diffraction gratings. Optical tweezers (cool example of light having momentum).
Ultra violet light
Ultraviolet radiation is an electromagnetic wavelength between 10-400 nanometers that can cause sunburn and skin cancer if exposed to for long periods without protection. It is used in astronomy to observe hot objects in space, as UV radiation is emitted. On Earth, UV light is used in fluorescent lamps, lasers, and for security features like watermarks on credit cards that are only visible under UV light. Prolonged exposure can damage DNA and increase risk of the skin cancer malignant melanoma.
Emily p
The document discusses the electromagnetic spectrum, which consists of radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. Each type of electromagnetic wave has a different wavelength and frequency, with radio waves having the longest wavelengths and lowest frequencies, and gamma rays having the shortest wavelengths and highest frequencies. Examples are given for how each type of electromagnetic wave is used, such as radios using radio waves, cell towers transmitting microwaves, heat lamps emitting infrared waves, stars emitting visible light, black lights using ultraviolet waves, X-rays being used to see broken bones, and neutron stars emitting gamma rays.
prueba
The document discusses the development of a Littrow spectrograph and its advantages over a classical spectrograph. It describes using the Littrow configuration to enable amateur astronomers to conduct research through spectroscopy. Details are provided on constructing the spectrograph, aligning it, and obtaining spectra of various astronomical objects using a DSLR camera mounted to a telescope.
Chapter 03 Tests
The document is a series of questions and answers about modern telescopes and astronomy. It discusses how modern telescopes use mirrors rather than lenses, how "seeing" refers to the quality of images affected by atmospheric conditions, and how different types of telescopes like the Hubble Space Telescope are useful for observing different wavelengths of light and regions of space.
Multiwavelength astronomy
Here's my presentation on "Multiwavelength Astronomy".I had presented it on National Astronomy Olympiad-2016,Nepal.
Light intensity/electromagnetic Waves/Wave-quantum Theory/Radioactivity
Brief introduction on
Light intensity quality,
Invisible spectrum,
EM radiation-properties,
Theory of wave and quanta
Radio-activity
Radio-activity/substances
Radio-activity: substances, law, curve, half life, decay factor etc.
Details about radium, cobalt, cesium
Sinar Agama
Gamma rays are a form of electromagnetic radiation that were discovered in 1900 by Paul Villard. They have the shortest wavelengths and highest frequencies of all electromagnetic waves, ranging from 10-11 to 10-14 meters. Gamma rays are produced through nuclear reactions and radioactive decay. They can pass through materials like metal and concrete due to their high energy. Common uses of gamma rays include medical applications like cancer treatment, industrial applications like defect detection, and food preservation.
Gamma Ray wave
Gamma rays are a form of electromagnetic radiation emitted from radioactive decay processes. They have short wavelengths between 10-5 to 0.1 nm and high frequencies between 1020-1025 Hz. Gamma rays were discovered in 1900 by Paul Ulrich Villard and occur naturally from processes like nuclear fusion and electron-positron annihilation. They are used in medicine for radiography, CT scans, and gamma knife surgery. Gamma knife surgery uses over 200 concentrated gamma rays to destroy targeted tumor tissue without damaging surrounding brain areas. Gamma rays can also have negative effects if overexposed, like cell damage and infertility.
Types of spectrometer IMA
Spectrometers are instruments that identify, measure, and analyze the specific wavelengths of light or other radiation absorbed, emitted, or scattered by chemical substances or physical samples. Common types of spectrometers include UV-visible spectroscopy, infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy, and mass spectroscopy. UV-visible spectroscopy uses light in the visible and near-UV and infrared ranges to determine concentrations of substances. Infrared spectroscopy analyzes the absorption of infrared radiation by chemical bonds to determine a sample's molecular structure. Raman spectroscopy detects the inelastic scattering of laser light to identify materials based on their molecular vibration and rotation signatures.
The electromagnetic spectrum
The document discusses the electromagnetic spectrum. It describes how electromagnetic waves can be classified based on their frequency and wavelength into different types of radiation including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each type of electromagnetic radiation has distinct characteristics and common uses. For example, radio waves are used to transmit audio and television signals, microwaves are used in radar and microwave ovens, and X-rays are used in medical imaging. The document also discusses hypotheses about dark matter particles called axions and the possibility of detecting gamma ray bursts from supernovae that could provide evidence about the nature of dark matter.
Atomic spectrum
This document discusses atomic spectra and how they can be used to identify elements. It explains that atoms emit and absorb light at specific frequencies when electrons jump between energy levels, and that each element has a unique atomic spectrum. A spectroscope can be used to separate light into its component frequencies, allowing scientists to determine the chemical composition of stars and perform flame tests by observing the atomic spectra emitted or absorbed.
Electromagnetic Spectrum (#EM SPECTRUM)
Oersted, Faraday, Maxwell, and Hertz contributed to the development of electromagnetic theory through key experiments and findings. Oersted discovered that electric currents create magnetic fields. Faraday showed that changing magnetic fields induce electric fields. Maxwell formulated equations showing the relationship between electricity and magnetism. Hertz provided experimental evidence of electromagnetic waves and their link to light.
Solarbox 3000(revision 2008)
The document summarizes the specifications and capabilities of the Solarbox 3000. It can simulate outdoor UV light conditions between 300-800 nm. Testing at 550 W/m2 of irradiation in the Solarbox is equivalent to 24 hours of exposure in Europe or 5.3 hours in Miami. Increasing the irradiation to 1000 W/m2 nearly doubles the acceleration. Exposure times in the Solarbox to simulate various months of natural light exposure are provided, ranging from 23 hours to simulate 1 month to 203 hours to simulate 9 months.
Aielli clil
The electromagnetic spectrum is the range of frequencies and wavelengths of electromagnetic radiation, from radio waves to gamma rays. It is divided into bands including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Microwave ovens utilize microwaves, centered around 2.45 GHz, to heat water molecules in food through dielectric heating. Dark matter, which accounts for 85% of matter in the universe, may consist partially of hypothetical axion particles that could transform between photons and axions when passing through magnetic fields, allowing detection of gamma ray bursts from supernovae.
Name _______________________________ NASA Video Tour of the E.docx
Name _______________________________
NASA Video: Tour of the Electromagnetic Spectrum (EMS)
Go to https://www.youtube.com/watch?v=HPcAWNlVl-8. This short video clip will introduce you to the Electromagnetic Spectrum. Complete this worksheet as you watch the video. You can pause the video to answer questions. For Part 1, in addition to the Introduction, complete the sections on Radio Waves, Microwaves, Infrared, Visible Light, UV, X-rays, and Gamma Rays. For Part 2, answer the questions and fill in the chart.
PART 1
Introduction (5:03)
1. What is the “it” that the world as we know it would not be able to exist without?
2. What are some (3) examples of things in everyday life that depend on waves from the EM spectrum?
3. How are EM waves produced?
4. Which waves on the EM spectrum have the lowest frequency and carry the least amount of energy?
5. Which waves are the shortest, highest energy waves in the spectrum?
6. What is the range of wavelengths that our eyes can see on the spectrum? This is called the visible light spectrum.
Radio Waves (3:39)
1. In what year were the first radio waves transmitted?
2. What are some objects we can use to compare the wavelength of radio waves?
3. Who is the scientist that discovered radio waves in 1888?
4. List the 3 heavenly bodies that were discovered using radio waves.
Microwaves (3:04)
1. What are 3 things that microwaves do?
2. Where do microwaves fall on the EM spectrum? Between what two other types of EM waves?
3. What do C-microwaves reveal to scientists?
4. What type of microwaves do GPS systems use?
Infrared Waves (5:23)
1. Even though we can’t see infrared waves, how can we sense its existence?
2. Do infrared waves have longer or shorter wavelengths than visible light?
3. What are the components of the “Earth Radiation Budget?”
4. What does studying the emitted and reflected infrared radiation help us to understand?
Visible Light Waves (4:50)
1. What is the only part of the spectrum that we can see?
2. What color or colors is sunlight?
3. What does Earth’s atmosphere generally look blue?
4. What causes the color of a sunset?
5. What does the sun produce more yellow light than any other color? What is its surface temperature?
6. How did visible light waves help scientists decipher a picture taken of Chaiten, Chile?
Ultraviolet Waves (3:40)
1. Why are bugs attracted to UV light?
2. What are the 3 regions that UV waves can be subdivided into?
3. Which type of UV rays are the harmful type that cause sunburn?
4. What does NASA’s L.A.M.P. look for?
X-Rays (2:50)
1. Who discovered bone x-rays in 1895?
2. What 2 elements has the MARS Rover detected in Martian rocks?
3. What 4 things can x-rays provide information about?
Gamma Rays (3:42)
1. What are gamma rays created by?
2. What are the 3 ways gamma rays are created naturally in Earth’s atmosphere?
3. What do doctors use gamma radiation to destroy?
4. What do gamma ra ...
em-spectrum-lessons-1.pptx
This document provides an overview of lessons on the electromagnetic spectrum for students. It includes learning objectives, descriptions of different types of electromagnetic radiation, and activities for students to research and learn about various parts of the spectrum. The document covers radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Students are tasked with learning the properties and order of the different radiations, as well as their uses, safety considerations, and impacts on society. Activities include experiments, research presentations, discussions, and assessments to check understanding.
P6 lesson part two
This document provides an overview of the lessons that will be covered in a module about radiation and waves. It focuses on lesson P6.7, which discusses electromagnetic waves with frequencies higher than visible light, including ultraviolet (UV) rays, X-rays, and gamma rays. The lesson objectives are to understand that these waves are ionizing radiation that can alter or damage living cells. Examples of sources, detectors, and uses of each type of wave are provided. Key concepts explained are that frequency increases and wavelength decreases as you move from radio waves to gamma rays in the electromagnetic spectrum.
electromagneticwaves-120829053329-phpapp02.pdf
1. This document discusses the electromagnetic spectrum, which includes electromagnetic waves ranging from radio waves to gamma rays. It describes the key properties and applications of different types of electromagnetic waves.
2. Students are instructed to read through the powerpoint presentation on electromagnetic waves and attempt an EM wave quiz within 60 minutes. The quiz grades will count towards their semester assessment.
3. The presentation covers the main components of the electromagnetic spectrum, the properties of all EM waves, and discusses the role and applications of different EM waves like radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Students are provided tips to remember the EM spectrum and visible light spectrum.
INTERVENTION ELECTROMAGNETIC SPECTRUM.pdf
This document provides a strategic intervention material on the electromagnetic spectrum for science learners. It includes activities to help students understand the key concepts of electromagnetic waves including their development, properties, applications and effects. The material guides students through reading, activities, assessments and references to build knowledge about electromagnetic theory and the different regions of the electromagnetic spectrum.
Electromagnetic Waves COT2.pptx
This document discusses electromagnetic waves. It begins with an opening prayer. The learning objectives are to describe how electromagnetic waves are produced and how they differ from each other. It also aims to explain the applications of electromagnetic waves and their detrimental effects. Students will work in groups on different activities to understand electromagnetic waves, such as creating a Frayer model map, analyzing a video, and reading a webpage about electromagnetic waves. They will consider how the frequency, wavelength, and energy of electromagnetic waves determine their safety. The document emphasizes identifying hazards and risks related to electromagnetic radiation exposure in the workplace.
SPECTROSCOPY.pdf
Spectroscopy involves analyzing the interaction of electromagnetic radiation with matter. Different regions of the electromagnetic spectrum are used to study different types of molecular motion and structure. UV-visible spectroscopy analyzes electronic transitions that occur when molecules absorb ultraviolet or visible light. The wavelength and intensity of absorbed light provides information about functional groups and molecular structure. Key concepts in UV-visible spectroscopy include chromophores, which are functional groups that absorb light in characteristic regions, and Beer's law, which states that absorbance is proportional to concentration.
Introduction to spectroscopy student
Spectroscopy is the study of how light interacts with matter and can provide information about a molecule's structure. Different types of electromagnetic radiation excite molecules to different energy states. Infrared spectroscopy analyzes molecular vibrations to determine functional groups, UV-visible spectroscopy analyzes electronic transitions to study conjugated systems, and NMR spectroscopy uses radio waves to analyze nuclear spin transitions and determine atomic connectivity. Together these techniques allow chemists to learn about molecular structures without being able to directly see individual molecules.
Module 17 wireless communication
Here are the key points about how information is carried by radio waves:
- Radio waves by themselves cannot carry information like sounds, messages, etc. They need to be modulated.
- Modulation involves overlaying a signal containing the information onto the radio wave. This encodes the information onto the wave.
- The main types of modulation are:
- Amplitude modulation (AM) - varies the amplitude of the wave while keeping frequency constant
- Frequency modulation (FM) - varies the frequency of the wave while keeping amplitude constant
- In AM broadcasting, the audio signal is used to vary the amplitude of the radio carrier wave. This encodes the sound onto the wave.
- In FM broadcasting, the audio signal
Radioactivity
The document discusses ionizing radiation and its applications. It describes three types of ionizing radiation - alpha particles, beta particles, and gamma rays. Alpha particles have the highest ionization density and shortest range, while gamma rays have the lowest ionization density and longest range. Ionizing radiation is used in applications like medical imaging, radiation therapy, smoke detectors, carbon dating, and detecting leaks. It can kill or damage living cells, making it useful for sterilization but also dangerous if not handled safely.
UV Spectroscopy
Spectroscopy is the study of the interaction between electromagnetic radiation and matter. Ultraviolet-visible (UV-Vis) spectroscopy involves using UV or visible light to analyze samples. UV-Vis spectroscopy can be used to identify organic and inorganic compounds, determine concentrations, and study reaction kinetics. The document provides details on the principles, instrumentation, and applications of UV-Vis spectroscopy, including qualitative and quantitative analysis of organic compounds, detection of functional groups and impurities, and determination of molecular structure.
Notes pb lab 06 part 1 the spactacular spectrum
The document discusses the electromagnetic spectrum and key objectives for students to understand it. It explains that the electromagnetic spectrum includes seven types of electromagnetic waves - radio waves, microwaves, infrared waves, visible light, ultraviolet light, X-rays, and gamma rays - which are arranged based on their wavelength and frequency. The document provides information about each type of electromagnetic wave, their properties, typical uses, and proportion of the overall spectrum. The objectives are for students to investigate and understand electromagnetic waves, compare the different types, describe applications of each type, and recognize that electromagnetic waves can travel without a medium.
X & Gamma Rays | Best report
You will not find better than this report is a wonderful summary of which has gathered a lot of valuable information
Big Bang Station Lab
The document describes an activity using a balloon to model the expansion of the universe. Students mark dots representing galaxies on an uninflated balloon and measure the distances between them. After inflating the balloon, the distances have increased, simulating the observed expansion of space in the actual universe. The activity shows that as the space between objects expands, the wavelength of light from distant galaxies appears redshifted. While useful, the balloon model has limitations and a three-dimensional model may better represent the large-scale structure of our expanding universe.
More Related Content
What's hot
Sinar Agama
Gamma rays are a form of electromagnetic radiation that were discovered in 1900 by Paul Villard. They have the shortest wavelengths and highest frequencies of all electromagnetic waves, ranging from 10-11 to 10-14 meters. Gamma rays are produced through nuclear reactions and radioactive decay. They can pass through materials like metal and concrete due to their high energy. Common uses of gamma rays include medical applications like cancer treatment, industrial applications like defect detection, and food preservation.
Gamma Ray wave
Gamma rays are a form of electromagnetic radiation emitted from radioactive decay processes. They have short wavelengths between 10-5 to 0.1 nm and high frequencies between 1020-1025 Hz. Gamma rays were discovered in 1900 by Paul Ulrich Villard and occur naturally from processes like nuclear fusion and electron-positron annihilation. They are used in medicine for radiography, CT scans, and gamma knife surgery. Gamma knife surgery uses over 200 concentrated gamma rays to destroy targeted tumor tissue without damaging surrounding brain areas. Gamma rays can also have negative effects if overexposed, like cell damage and infertility.
Types of spectrometer IMA
Spectrometers are instruments that identify, measure, and analyze the specific wavelengths of light or other radiation absorbed, emitted, or scattered by chemical substances or physical samples. Common types of spectrometers include UV-visible spectroscopy, infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy, and mass spectroscopy. UV-visible spectroscopy uses light in the visible and near-UV and infrared ranges to determine concentrations of substances. Infrared spectroscopy analyzes the absorption of infrared radiation by chemical bonds to determine a sample's molecular structure. Raman spectroscopy detects the inelastic scattering of laser light to identify materials based on their molecular vibration and rotation signatures.
The electromagnetic spectrum
The document discusses the electromagnetic spectrum. It describes how electromagnetic waves can be classified based on their frequency and wavelength into different types of radiation including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each type of electromagnetic radiation has distinct characteristics and common uses. For example, radio waves are used to transmit audio and television signals, microwaves are used in radar and microwave ovens, and X-rays are used in medical imaging. The document also discusses hypotheses about dark matter particles called axions and the possibility of detecting gamma ray bursts from supernovae that could provide evidence about the nature of dark matter.
Atomic spectrum
This document discusses atomic spectra and how they can be used to identify elements. It explains that atoms emit and absorb light at specific frequencies when electrons jump between energy levels, and that each element has a unique atomic spectrum. A spectroscope can be used to separate light into its component frequencies, allowing scientists to determine the chemical composition of stars and perform flame tests by observing the atomic spectra emitted or absorbed.
Electromagnetic Spectrum (#EM SPECTRUM)
Oersted, Faraday, Maxwell, and Hertz contributed to the development of electromagnetic theory through key experiments and findings. Oersted discovered that electric currents create magnetic fields. Faraday showed that changing magnetic fields induce electric fields. Maxwell formulated equations showing the relationship between electricity and magnetism. Hertz provided experimental evidence of electromagnetic waves and their link to light.
Solarbox 3000(revision 2008)
The document summarizes the specifications and capabilities of the Solarbox 3000. It can simulate outdoor UV light conditions between 300-800 nm. Testing at 550 W/m2 of irradiation in the Solarbox is equivalent to 24 hours of exposure in Europe or 5.3 hours in Miami. Increasing the irradiation to 1000 W/m2 nearly doubles the acceleration. Exposure times in the Solarbox to simulate various months of natural light exposure are provided, ranging from 23 hours to simulate 1 month to 203 hours to simulate 9 months.
Aielli clil
The electromagnetic spectrum is the range of frequencies and wavelengths of electromagnetic radiation, from radio waves to gamma rays. It is divided into bands including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Microwave ovens utilize microwaves, centered around 2.45 GHz, to heat water molecules in food through dielectric heating. Dark matter, which accounts for 85% of matter in the universe, may consist partially of hypothetical axion particles that could transform between photons and axions when passing through magnetic fields, allowing detection of gamma ray bursts from supernovae.
What's hot (8)
Similar to Discovering em spectrum
Name _______________________________ NASA Video Tour of the E.docx
Name _______________________________
NASA Video: Tour of the Electromagnetic Spectrum (EMS)
Go to https://www.youtube.com/watch?v=HPcAWNlVl-8. This short video clip will introduce you to the Electromagnetic Spectrum. Complete this worksheet as you watch the video. You can pause the video to answer questions. For Part 1, in addition to the Introduction, complete the sections on Radio Waves, Microwaves, Infrared, Visible Light, UV, X-rays, and Gamma Rays. For Part 2, answer the questions and fill in the chart.
PART 1
Introduction (5:03)
1. What is the “it” that the world as we know it would not be able to exist without?
2. What are some (3) examples of things in everyday life that depend on waves from the EM spectrum?
3. How are EM waves produced?
4. Which waves on the EM spectrum have the lowest frequency and carry the least amount of energy?
5. Which waves are the shortest, highest energy waves in the spectrum?
6. What is the range of wavelengths that our eyes can see on the spectrum? This is called the visible light spectrum.
Radio Waves (3:39)
1. In what year were the first radio waves transmitted?
2. What are some objects we can use to compare the wavelength of radio waves?
3. Who is the scientist that discovered radio waves in 1888?
4. List the 3 heavenly bodies that were discovered using radio waves.
Microwaves (3:04)
1. What are 3 things that microwaves do?
2. Where do microwaves fall on the EM spectrum? Between what two other types of EM waves?
3. What do C-microwaves reveal to scientists?
4. What type of microwaves do GPS systems use?
Infrared Waves (5:23)
1. Even though we can’t see infrared waves, how can we sense its existence?
2. Do infrared waves have longer or shorter wavelengths than visible light?
3. What are the components of the “Earth Radiation Budget?”
4. What does studying the emitted and reflected infrared radiation help us to understand?
Visible Light Waves (4:50)
1. What is the only part of the spectrum that we can see?
2. What color or colors is sunlight?
3. What does Earth’s atmosphere generally look blue?
4. What causes the color of a sunset?
5. What does the sun produce more yellow light than any other color? What is its surface temperature?
6. How did visible light waves help scientists decipher a picture taken of Chaiten, Chile?
Ultraviolet Waves (3:40)
1. Why are bugs attracted to UV light?
2. What are the 3 regions that UV waves can be subdivided into?
3. Which type of UV rays are the harmful type that cause sunburn?
4. What does NASA’s L.A.M.P. look for?
X-Rays (2:50)
1. Who discovered bone x-rays in 1895?
2. What 2 elements has the MARS Rover detected in Martian rocks?
3. What 4 things can x-rays provide information about?
Gamma Rays (3:42)
1. What are gamma rays created by?
2. What are the 3 ways gamma rays are created naturally in Earth’s atmosphere?
3. What do doctors use gamma radiation to destroy?
4. What do gamma ra ...
em-spectrum-lessons-1.pptx
This document provides an overview of lessons on the electromagnetic spectrum for students. It includes learning objectives, descriptions of different types of electromagnetic radiation, and activities for students to research and learn about various parts of the spectrum. The document covers radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Students are tasked with learning the properties and order of the different radiations, as well as their uses, safety considerations, and impacts on society. Activities include experiments, research presentations, discussions, and assessments to check understanding.
P6 lesson part two
This document provides an overview of the lessons that will be covered in a module about radiation and waves. It focuses on lesson P6.7, which discusses electromagnetic waves with frequencies higher than visible light, including ultraviolet (UV) rays, X-rays, and gamma rays. The lesson objectives are to understand that these waves are ionizing radiation that can alter or damage living cells. Examples of sources, detectors, and uses of each type of wave are provided. Key concepts explained are that frequency increases and wavelength decreases as you move from radio waves to gamma rays in the electromagnetic spectrum.
electromagneticwaves-120829053329-phpapp02.pdf
1. This document discusses the electromagnetic spectrum, which includes electromagnetic waves ranging from radio waves to gamma rays. It describes the key properties and applications of different types of electromagnetic waves.
2. Students are instructed to read through the powerpoint presentation on electromagnetic waves and attempt an EM wave quiz within 60 minutes. The quiz grades will count towards their semester assessment.
3. The presentation covers the main components of the electromagnetic spectrum, the properties of all EM waves, and discusses the role and applications of different EM waves like radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Students are provided tips to remember the EM spectrum and visible light spectrum.
INTERVENTION ELECTROMAGNETIC SPECTRUM.pdf
This document provides a strategic intervention material on the electromagnetic spectrum for science learners. It includes activities to help students understand the key concepts of electromagnetic waves including their development, properties, applications and effects. The material guides students through reading, activities, assessments and references to build knowledge about electromagnetic theory and the different regions of the electromagnetic spectrum.
Electromagnetic Waves COT2.pptx
This document discusses electromagnetic waves. It begins with an opening prayer. The learning objectives are to describe how electromagnetic waves are produced and how they differ from each other. It also aims to explain the applications of electromagnetic waves and their detrimental effects. Students will work in groups on different activities to understand electromagnetic waves, such as creating a Frayer model map, analyzing a video, and reading a webpage about electromagnetic waves. They will consider how the frequency, wavelength, and energy of electromagnetic waves determine their safety. The document emphasizes identifying hazards and risks related to electromagnetic radiation exposure in the workplace.
SPECTROSCOPY.pdf
Spectroscopy involves analyzing the interaction of electromagnetic radiation with matter. Different regions of the electromagnetic spectrum are used to study different types of molecular motion and structure. UV-visible spectroscopy analyzes electronic transitions that occur when molecules absorb ultraviolet or visible light. The wavelength and intensity of absorbed light provides information about functional groups and molecular structure. Key concepts in UV-visible spectroscopy include chromophores, which are functional groups that absorb light in characteristic regions, and Beer's law, which states that absorbance is proportional to concentration.
Introduction to spectroscopy student
Spectroscopy is the study of how light interacts with matter and can provide information about a molecule's structure. Different types of electromagnetic radiation excite molecules to different energy states. Infrared spectroscopy analyzes molecular vibrations to determine functional groups, UV-visible spectroscopy analyzes electronic transitions to study conjugated systems, and NMR spectroscopy uses radio waves to analyze nuclear spin transitions and determine atomic connectivity. Together these techniques allow chemists to learn about molecular structures without being able to directly see individual molecules.
Module 17 wireless communication
Here are the key points about how information is carried by radio waves:
- Radio waves by themselves cannot carry information like sounds, messages, etc. They need to be modulated.
- Modulation involves overlaying a signal containing the information onto the radio wave. This encodes the information onto the wave.
- The main types of modulation are:
- Amplitude modulation (AM) - varies the amplitude of the wave while keeping frequency constant
- Frequency modulation (FM) - varies the frequency of the wave while keeping amplitude constant
- In AM broadcasting, the audio signal is used to vary the amplitude of the radio carrier wave. This encodes the sound onto the wave.
- In FM broadcasting, the audio signal
Radioactivity
The document discusses ionizing radiation and its applications. It describes three types of ionizing radiation - alpha particles, beta particles, and gamma rays. Alpha particles have the highest ionization density and shortest range, while gamma rays have the lowest ionization density and longest range. Ionizing radiation is used in applications like medical imaging, radiation therapy, smoke detectors, carbon dating, and detecting leaks. It can kill or damage living cells, making it useful for sterilization but also dangerous if not handled safely.
UV Spectroscopy
Spectroscopy is the study of the interaction between electromagnetic radiation and matter. Ultraviolet-visible (UV-Vis) spectroscopy involves using UV or visible light to analyze samples. UV-Vis spectroscopy can be used to identify organic and inorganic compounds, determine concentrations, and study reaction kinetics. The document provides details on the principles, instrumentation, and applications of UV-Vis spectroscopy, including qualitative and quantitative analysis of organic compounds, detection of functional groups and impurities, and determination of molecular structure.
Notes pb lab 06 part 1 the spactacular spectrum
The document discusses the electromagnetic spectrum and key objectives for students to understand it. It explains that the electromagnetic spectrum includes seven types of electromagnetic waves - radio waves, microwaves, infrared waves, visible light, ultraviolet light, X-rays, and gamma rays - which are arranged based on their wavelength and frequency. The document provides information about each type of electromagnetic wave, their properties, typical uses, and proportion of the overall spectrum. The objectives are for students to investigate and understand electromagnetic waves, compare the different types, describe applications of each type, and recognize that electromagnetic waves can travel without a medium.
X & Gamma Rays | Best report
You will not find better than this report is a wonderful summary of which has gathered a lot of valuable information
Big Bang Station Lab
The document describes an activity using a balloon to model the expansion of the universe. Students mark dots representing galaxies on an uninflated balloon and measure the distances between them. After inflating the balloon, the distances have increased, simulating the observed expansion of space in the actual universe. The activity shows that as the space between objects expands, the wavelength of light from distant galaxies appears redshifted. While useful, the balloon model has limitations and a three-dimensional model may better represent the large-scale structure of our expanding universe.
radioisotopetechnique-161107054511.pdf
This document summarizes a seminar report on radioisotopes presented by Abhishek A. Giri. It defines radioisotopes as unstable isotopes that emit radiation during radioactive decay. It discusses several applications of radioisotopes including medical tracers, sterilization, and food sterilization. It also describes methods of detecting and measuring radioactivity including gas ionization, scintillation counting, and autoradiography.
Radioisotope technique and methods
An isotope is one of two or more atoms having the same atomic number but different mass numbers.
Unstable isotopes are called Radioisotopes.
uses of radioisotopes are many which are discussed in this slide.
Spectroscopy
This document is a 38-page seminar report on spectroscopy submitted by two students, Arpit Modh and Parth Kasodariya. It includes an introduction to spectroscopy, descriptions of various spectroscopy techniques like atomic absorption spectroscopy, infrared absorption spectroscopy, and ultraviolet-visible spectroscopy. The report covers principles, instrumentation, applications, and more for different spectroscopy methods. It aims to provide a basic review of spectroscopy and its uses in various important fields like structure analysis.
Radioactivity
The document provides an introduction to radioactivity, including the three main types of radioactive emissions (alpha, beta, gamma), their penetrating properties, safe handling of radioactive materials, and uses of radioisotopes. It defines key terms and includes sample test questions to assess understanding.
Taylor - Ultraviolet Light
Ultraviolet light was discovered in 1801 by German physicist Johann Wilhelm Ritter. It is a type of electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays, between 300 to 400 nanometers. UV radiation can damage components of paper, photographs, inks and other materials by causing photoionization which alters atoms and molecules. The UV spectrum is divided into UVA, UVB, and UVC bands with different wavelengths. The sun is a major natural source of UV rays, with UVA making up most of the UV that reaches Earth. UV exposure can benefit humans by producing vitamin D but too much causes sunburns and skin damage. UV light has applications in security, forensics
Scanning electron microscopy
Electron microscopes use beams of electrons rather than light to image objects at a very fine scale. The scanning electron microscope (SEM) was developed in the 1930s-1960s to overcome limitations of light microscopes. An SEM scans samples with a high-energy electron beam, producing signals containing information about surface topography, composition, and other properties. Key advantages of SEMs over light microscopes are their greater magnification, depth of field, and resolution. Proper sample preparation including cleaning, fixation, dehydration and coating is required to image non-conductive biological samples in the SEM's vacuum environment.
Similar to Discovering em spectrum (20)
Name _______________________________ NASA Video Tour of the E.docx
Name _______________________________ NASA Video Tour of the E.docx
Recently uploaded
快速办理(UAM毕业证书)马德里自治大学毕业证学位证一模一样
学校原件一模一样【微信：741003700 】《(UAM毕业证书)马德里自治大学毕业证学位证》【微信：741003700 】学位证，留信认证（真实可查，永久存档）原件一模一样纸张工艺/offer、雅思、外壳等材料/诚信可靠,可直接看成品样本，帮您解决无法毕业带来的各种难题！外壳，原版制作，诚信可靠，可直接看成品样本。行业标杆！精益求精，诚心合作，真诚制作！多年品质 ,按需精细制作，24小时接单,全套进口原装设备。十五年致力于帮助留学生解决难题，包您满意。
本公司拥有海外各大学样板无数，能完美还原。
1:1完美还原海外各大学毕业材料上的工艺：水印，阴影底纹，钢印LOGO烫金烫银，LOGO烫金烫银复合重叠。文字图案浮雕、激光镭射、紫外荧光、温感、复印防伪等防伪工艺。材料咨询办理、认证咨询办理请加学历顾问Q/微741003700
【主营项目】
一.毕业证【q微741003700】成绩单、使馆认证、教育部认证、雅思托福成绩单、学生卡等！
二.真实使馆公证(即留学回国人员证明,不成功不收费)
三.真实教育部学历学位认证（教育部存档！教育部留服网站永久可查）
四.办理各国各大学文凭(一对一专业服务,可全程监控跟踪进度)
如果您处于以下几种情况：
◇在校期间，因各种原因未能顺利毕业……拿不到官方毕业证【q/微741003700】
◇面对父母的压力，希望尽快拿到；
◇不清楚认证流程以及材料该如何准备；
◇回国时间很长，忘记办理；
◇回国马上就要找工作，办给用人单位看；
◇企事业单位必须要求办理的
◇需要报考公务员、购买免税车、落转户口
◇申请留学生创业基金
留信网认证的作用:
1:该专业认证可证明留学生真实身份
2:同时对留学生所学专业登记给予评定
3:国家专业人才认证中心颁发入库证书
4:这个认证书并且可以归档倒地方
5:凡事获得留信网入网的信息将会逐步更新到个人身份内，将在公安局网内查询个人身份证信息后，同步读取人才网入库信息
6:个人职称评审加20分
7:个人信誉贷款加10分
8:在国家人才网主办的国家网络招聘大会中纳入资料，供国家高端企业选择人才
waterlessdyeingtechnolgyusing carbon dioxide chemicalspdf
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
SAR of Medicinal Chemistry 1st by dk.pdf
In this presentation include the prototype drug SAR on thus or with their examples .
Syllabus of Second Year B. Pharmacy
2019 PATTERN.
Immersive Learning That Works: Research Grounding and Paths Forward
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
The debris of the ‘last major merger’ is dynamically young
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Compexometric titration/Chelatorphy titration/chelating titration
Classification
Metal ion ion indicators
Masking and demasking reagents
Estimation of Magnisium sulphate
Calcium gluconate
Complexometric Titration/ chelatometry titration/chelating titration, introduction, Types-
1.Direct Titration
2.Back Titration
3.Replacement Titration
4.Indirect Titration
Masking agent, Demasking agents
formation of complex
comparition between masking and demasking agents,
Indicators/Metal ion indicators/ Metallochromic indicators/pM indicators,
Visual Technique,PM indicators (metallochromic), Indicators of pH, Redox Indicators
Instrumental Techniques-Photometry
Potentiometry
Miscellaneous methods.
Complex titration with EDTA.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
Katherine Romanak - Geologic CO2 Storage.pdf
Presented at June 6-7 Texas Alliance of Groundwater Districts Business Meeting
Bob Reedy - Nitrate in Texas Groundwater.pdf
Presented at June 6-7 Texas Alliance of Groundwater Districts Business Meeting
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.Equivariant neural networks and representation theory
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
11.1 Role of physical biological in deterioration of grains.pdf
Storagedeteriorationisanyformoflossinquantityandqualityofbio-materials.
Themajorcausesofdeteriorationinstorage
•Physical
•Biological
•Mechanical
•Chemical
Storageonlypreservesquality.Itneverimprovesquality.
Itisadvisabletostartstoragewithqualityfoodproduct.Productwithinitialpoorqualityquicklydepreciates
Micronuclei test.M.sc.zoology.fisheries.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
Pests of Storage_Identification_Dr.UPR.pdf
InIndia-post-harvestlosses-unscientificstorage,insects,rodents,micro-organismsetc.,accountforabout10percentoftotalfoodgrains
Graininfestation
Directdamage
Indirectly
•theexuviae,skin,deadinsects
•theirexcretawhichmakefoodunfitforhumanconsumption
About600speciesofinsectshavebeenassociatedwithstoredgrainproducts
100speciesofinsectpestsofstoredproductscauseeconomiclosses
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
ESR spectroscopy in liquid food and beverages.pptx
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Sharlene Leurig - Enabling Onsite Water Use with Net Zero Water
Sharlene Leurig - Enabling Onsite Water Use with Net Zero WaterTexas Alliance of Groundwater Districts
Presented at June 6-7 Texas Alliance of Groundwater Districts Business MeetingRecently uploaded (20)
waterlessdyeingtechnolgyusing carbon dioxide chemicalspdf
waterlessdyeingtechnolgyusing carbon dioxide chemicalspdf
Immersive Learning That Works: Research Grounding and Paths Forward
Immersive Learning That Works: Research Grounding and Paths Forward
The debris of the ‘last major merger’ is dynamically young
The debris of the ‘last major merger’ is dynamically young
Compexometric titration/Chelatorphy titration/chelating titration
Compexometric titration/Chelatorphy titration/chelating titration
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...
Equivariant neural networks and representation theory
Equivariant neural networks and representation theory
Basics of crystallography, crystal systems, classes and different forms
Basics of crystallography, crystal systems, classes and different forms
11.1 Role of physical biological in deterioration of grains.pdf
11.1 Role of physical biological in deterioration of grains.pdf
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...
ESR spectroscopy in liquid food and beverages.pptx
ESR spectroscopy in liquid food and beverages.pptx
Sharlene Leurig - Enabling Onsite Water Use with Net Zero Water
Sharlene Leurig - Enabling Onsite Water Use with Net Zero Water
Discovering em spectrum
- 1. Powell/Astronomy How can we detect Electromagnetic radiation outside the visible spectrum? How are the various type of waves used in astronomy? 1. The picture above shows the varying frequency and wavelength in the EM spectrum. 2. This diagram shows a 3-D view of EM waves. We will demonstrate this 3-D structure in class using polarizing lenses. Have you heard of polarized sunglasses? How do they work? 3. 4. Examine the polarizedfilterstosee how itaffectsthe amountof lightthat can be seen. 5. Whatdid you observeand why did this happen? (thisisa lab to be performedinclass) Let’slookat the varioustypesof radiation andhow theycan be detectedandusedinastronomy. 6. Radio waves
- 2. Powell/Astronomy Start withthisYouTube videoonradiowaves https://www.youtube.com/watch?v=kxLcwIMYmr0 Thenwatch an Edpuzzle videoonNASA radiowaves Go to thiswebsite https://science.nasa.gov/ems/05_radiowaves andanswerthese questions: 1. Who discoveredradiowavesinlate 1800s? Here is a linkabouthisdiscoveries https://nationalmaglab.org/education/magnet- academy/history-of-electricity-magnetism/pioneers/heinrich-hertz 2. What are radiotelescopesusedfor? 3. If we use a radiotelescope turnedto408 MHz what wouldbe see inthe sky? 7. Microwaves Watch edpuzzle NASA microwaves Go to thisNASA site andanswerthese questions https://science.nasa.gov/ems/06_microwaves 1. List 3 usesof microwaves asdiscussed on thiswebsite. 2. What was discoveredbyscientistsinBellLaboratorythatprovidedinformationthat supportedthe bigbangtheory? 8. IR or infraredradiation Watch EDpuzzle NASA Infraredwaves Go to thisNASA site toanswerthese questions https://science.nasa.gov/ems/07_infraredwaves 1. Who discoveredIRwavesandinwhatyear? 2. What didthe Cassini spacecraftobserve? 3. What isthe purpose of the JamesWebbtelescope? 9. Ultravioletlight Watch Edpuzzle NASA UV rays Go to thisNASA site toanswerthese questions https://science.nasa.gov/ems/10_ultravioletwaves 1. What are the 3 typesof UV classifications? 2. What colorsare the coolertemperaturesinspace? 3. Who discoveredUV lightandinwhatyear? 10. X-Rays Watch EDpuzzle NASA X-rays Go to thisNASA site toanswerthese questions https://science.nasa.gov/ems/11_xrays 1. X-Raysare aboutthe size of what? 2. Who discoveredX-raysandwhen? 3. Our sun’scorona expelsmostlywhattype of rays?
- 3. Powell/Astronomy 4. The spiritNOVA useswhichX-Raystodetectwhaton Mars? 11. ɣ (gamma) radiation Watch EDpuzzle NASA X-rays Go to thisNASA site toanswerthese questions https://science.nasa.gov/ems/12_gammarays 1. How are gamma rays producedonearth? 2. How are gamma rays detectedinspace? 3. What are some sourcesof gamma rays inspace?