November 18, 2013

November 18, 2013

November 18, 2013Electromagnetic RadiationObjectivesAt the end of class, you will be able to:List the forms of electromagnetic radiationFind wavelength or frequency of electromagnetic radiation

Waves and ParticlesParticles are solid matterWaves are movement in matter, like an ocean wave or a wave at a football game

Electromagnetic RadiationEnergy that travels through space as a wave

EXAMPLES:Gamma raysX-raysUltraviolet raysVisible lightInfrared MicrowavesRadiowaves Electromagnetic spectrumIn a vacuum all electromagnetic radiation travels at the speed of light.This speed is c = 3.0 108 m/s

WavelengthSymbol: (lambda) Units: m (meter)Distance between corresponding points on a wave

FrequencySymbol: (nu)Units: s-1, Hz, 1/sNumber of waves that pass a point per second

Each form of light has different wavelength and frequency, but they all have the SAME SPEED

As wavelength ______________, frequency _______________.

As wavelength ______________, frequency ________________.

increasesdecreasesdecreasesincreasesThe big equation for EM radiation:c =

PRACTICE:1. What is the wavelength of electromagnetic radiation with a frequency of 2.0 1015 Hz? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light?Use formula: c = Identify known information: c = 3.0 x 108 m/s = 2.0 1015 HzPlug known information into formula:3.0 x 108 m/s = (2.0 1015 Hz)Solve for = (3.0 x 108 m/s)/(2.0 1015 Hz) = 1.5 10-7 m

Ultraviolet lightPRACTICE:2. What is the frequency of light with a wavelength of 4.5 10-7 m? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light?Use formula: c = Identify known information: c = 3.0 x 108 m/s = 4.5 10-7 mPlug known information into formula:3.0 x 108 m/s = (4.5 10-7 m) Solve for = (3.0 x 108 m/s)/(4.5 10-7 m) = 6.67 1014 Hz

Visible light BlueVisible light BluePRACTICE:3. What is the wavelength of electromagnetic radiation with a frequency of 5.85 1018 Hz? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light?Use formula: c = Identify known information: c= 3.0 x 108 m/sv = 5.85 x 1018 Hz Plug known information into formula:3.0 x 108 m/s = (5.85 x 1018 s-1)Solve for = (3.0 x 108 m/s)/(5.85 x 1018 s-1) = = 5.13 x 10-11 m

Use formula: c = Identify known information: c = 3.0 x 108 m/s = 4.5 10-7 mPlug known information into formula:3.0 x 108 m/s = (4.5 10-7 m) Solve for = (3.0 x 108 m/s)/(4.5 10-7 m) = 6.67 1014 Hz

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Gamma Rays (or X-rays) The wavelengths overlap sometimesPRACTICE:4. What is the frequency of light with a wavelength of 64 cm? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light?

Hint: make sure all variables are in units of m! 64 cm | 1m = 0.64 m 100 cmPRACTICE:4. What is the frequency of light with a wavelength of 0.64 m? Where is this in the electromagnetic spectrum? If it is visible light, what color is the light?Use formula: c = Identify known information: c= 3.0 x 108 m/s = 0.64 mPlug known information into formula:3.0 x 108 m/s = (0.64m) Solve for = (3.0 x 108 m/s)/(0.64 m) = = 4.69 x 108 Hz

Radio WavesCheck: What is wavelength?What is the unit for wavelength?What is frequency?What is the unit for frequency?How can you find one if you know the other?