2Types of Waves Mechanical Waves need matter (medium) to travel through Electromagnetic Waves can travel through empty space
3Mechanical WavesMay be longitudinal (compression)Or transverse
4Transverse Waves Transverse waves move like a snake going up and down Light energy moves in transverse waves
5Parts of a transverse wave: As wavelength increases, frequency decreasesWavelengthAmplitudeCrestTroughHow often = Frequency
6Compression WavesCompression waves move like a worm, squeezing and releasingSound energy moves in compression waves
7Longitudinal/Compression Waves – energy must move along the medium while traveling forward
8Transverse Both Longitudinal Moves in compressions (pulses) in same direction the wave doesExample: sound wavesBoth have a frequencywavelength, amplitudeBoth transfer energy from one place to anotherWave moves up and down or side to side while traveling forwardExample: light waves
9Review : Which letter shows the amplitude of the wave at right? Which letter shows a wavelength of the wave at right?When frequency increases, what happens to the wavelength?bcda
11Objectives -Define electromagnetic radiation. -Identify positive and negative effects of waves on human activities-Compare and contrast the differing frequencies and energy levels of waves in the electromagnetic spectrum
12Focus QuestionWhat effect does increasing frequency and wavelength have on energy of waves?
13Electromagnetic (EM) waves Light is an electromagnetic wave.EM waves are made up of 2 fields: electric and magnetic.
14All EM waves travel at the same speed the speed of light (c). c = λ f
16Radio Waves Longest wavelengths and lowest frequencies. Lowest energy. Used to carry sound and picture info to TVs and radios.
17Microwaves More energy than radio waves. Used in microwave OVENS and radar guns.Draw a picture of something that will help you remember microwaves.
18This is a microwave OVEN Note: MicrowavesThis is a microwave OVENThis is a MICROWAVEMicrowaves are used IN microwave ovens to help cook the food.Microwaves are EM waves. Microwave OVENS are NOT EM waves.
19Infrared Waves More energy than radio waves and microwaves. Infrared waves from the sun make you feel warm.Draw a picture of something that will help you remember infrared waves.
20Visible Light The kind of light that humans can see. Includes the colors ROY G BIV.Red has long waves; violet has short wavesDraw a picture of something that will remind you of visible light.
21Ultraviolet (UV) Light More energy than visible lightUsed to kill bacteria on food or surgical instruments.UV rays from the sun can cause sunburn or cancer.Absorbed by the ozone layer.Draw a picture of something that will remind you of Ultraviolet Light.
22X-Rays Can be used to take pictures of the inside of your body. Have large amounts of energy.Draw a picture of something that will remind you of X-Rays
23Gamma Rays Carry the most energy of all waves Highest frequency & shortest wavelengthUsed to kill cancer cellsGiven off in nuclear reactionsMost dangerous to humans!Draw a picture of something that will remind you of gamma rays.
24Look at your spectrum.What happens to the wavelength of EM waves as you move right along the spectrum?The wavelength gets SHORTER as you move up the spectrum.What happens to the frequency of EM waves as you move up the spectrum to the right?The frequency gets HIGHER as you move up the spectrum.
25Which waves have the least energy? Waves on the left have less energy. Radio waves have the least.Which waves have the most energy?Waves on the right have more energy. Gamma rays have the most.
26Which waves have a longer wavelength? Radio or Gamma?Ultraviolet or Infrared?Microwaves or Visible Light?Which waves have a higher frequency?Visible Light or X-Rays?Microwaves or Infrared?Ultraviolet or Visible Light?
27Which waves have more energy? Radio or Gamma?Ultraviolet or Infrared?Microwaves or Visible Light?
28Answer this on the back of your EMS: There are many types of EM waves. Which types do you think are the best or the most useful? Pick 1 or 2, and explain to me why you chose them. Write at least 4 sentences.This will be graded!