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09 November 2018 (P1.5.1b) E-Mag Waves Describe uses for different parts of the E-M spectrum. (D) Calculate velocity of E-M waves. (C) Describe and evaluate methods to reduce the risk from radiation (D-B) Key words Diffraction Electromagnetic Frequency Gamma rays Infra-Red Microwave Radio Risk Spectrum Ultra-Violet UV Visible Light Wavelength X-rays S: Which radiation worries you the most? S: Risky radiation PDF article (HT) S:True or False Sound travels faster through air than light does. Light waves are transverse waves. Sound waves are longitudinal waves. Sound can travel through a vacuum. Sound travels faster in solids than in air. Light travels faster through opaque objects than it does through glass. Sound waves cannot travel through water. Objects cannot travel faster than the speed of sound. Sounds are produced by vibrations. S:Starter Like all waves, light and sound waves both transfer ______. Light waves are ______ and sound waves are ______. The wavelength of a sound wave is the distance between two adjacent ______. The speed of ______ in air is m/s and the speed of _______ in air is about 330 m/s. This is why ______ often arrives before ______. 2
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Visible Light
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Infrared Rays
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Microwaves
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Radio Waves
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Ultraviolet Rays
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X Rays
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Gamma Rays
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Name that wave Each box requires a heading (type of wave)
1st task one person from each group Look for the master sheets and locate where each wave is on the spectrum Go back to your group, report your findings Scribes record each wave in its relevant box on the spectrum
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Name that wave Instructions Work in table groups
Read the clues, have a chat, look around the room for the information sheets Name that wave, locate that wave on the spectrum Transfer the information to your worksheet Be careful you only have one chance, no second worksheets You only have 3 minutes per wave to do all the above
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Name that wave I have a very short wavelength
Exhibit high energy levels I am used in security checks at the airport I have a high frequency Be very careful, I can cause cancer
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Name that wave I have a short wavelength --- thousands of a mm
You really need me I have a medium frequency Don’t look now I can cause blindness I exhibit moderate energy levels Cameras need me to take pictures
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Name that wave I am used in thermal imaging
I exhibit a wavelength of less than a mm Ok it’s moderate energy levels for me A low frequency wave I can cause burns
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Name that wave I have the shortest wavelength
Brilliant I can be used to cure cancer But be careful I can cause cancer as well I have the highest frequency I contain the most energy
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Name that wave I can be used in communication
I have the longest wavelength I have low energy levels I display a low wave frequency Harmless to humans
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Name that wave I am used in communications and cooking
I have a wavelength of a few cm I display a low wave frequency Be careful, I can cook and kill cells But I have a low energy level
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Name that wave Short wavelength Used in invisible ink, reflective dyes
Moderate energy levels Can cause burns and cancer Medium frequency
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Effect of electromagnetic waves
Teacher notes This matching activity could be used as a plenary or revision exercise on electromagnetic waves and how they affect living tissues. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.
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Red Men In Vans Use X-Ray Guns
Mnemonic Make up your own mnemonic to help you remember the Electromagnetic Spectrum. Red Men In Vans Use X-Ray Guns
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Silent working As the spectrum moves from radio waves to gamma waves
the frequency of the waves increases Write a sentence on each arrow on your worksheet describing any links between energy and wave frequency
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