1. CHAPTER 9: WAVES & LIGHT (& Sound)
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Waves carry energy from one place to another
K. Wilkinson 2015 Adapted from D. L. Power,Revised 1/20/01

2. Label the parts of the wave 
1. NATURE OF WAVES
Wave – any disturbance that transfers energy from one place to another without transferring matter.
Types of Waves
1. Mechanical Waves, which require a medium.
Transverse – moves up and down, examples are water and seismic waves.
Longitudinal – moves forward and backward, example is sound waves
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Label the parts of the wave 

3. Can Sound travel through space?
Nature of Waves…
2. Electromagnetic (EM) Waves, can travel through space!
Light, radio, micro, infrared, xray, ultraviolet and gamma
Wave Interactions
*Absorption
Transmission
*Reflection
*Refraction
Diffraction
Can Sound travel through space?

4. NATURE OF WAVES….
Wavelength measures the distance between two crests or troughs
Long WL have a very low frequency
Short WL have a very high frequency
Frequency measures how often the wave passes through a point within a second
Low freq. waves have low energy
High freq. waves have high energy
These characteristics only differ in a medium, they do not effect EM waves in space.

5. 2. ELECTROMAGNETIC WAVES (EM WAVES)
Vibrating electric and magnetic energy, moving through space or some medium at the speed of light
Speed in Vacuum
300,000 km/sec or 186,000 mi/sec
Speed in Other Materials
Slower in Air, Water, Glass

6. 3. ELECTROMAGNETIC RADIATION
heat
The waves (or energy) that is transferred through space or a vacuum
Only method for the Sun to get its heat energy to Earth!

7. 4. ELECTROMAGNETIC SPECTRUM
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8. EM Spectrum… Lowest Frequency
RADIO WAVES
Modulation variation of amplitude or frequency when waves are broadcast
AM – amplitude modulation
Carries audio for T.V. Broadcasts
Longer wavelength so can bend around hills
FM – frequency modulation
Carries video for T.V. Broadcasts

9. EM Spectrum… Low Frequency
MICRO WAVES
EM waves used to cook food in micro ovens
Also used to cellular phone communication and radar.
INFRARED RAYS (IR)
Used for cooking, medicine, T.V. remote controls and night vision

10. EM Spectrum…. VISIBLE LIGHT Light we can see
ROYGBIV – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet.
Largest to Smallest Wavelength.

11. EM Spectrum…. High Freq ULTRAVIOLET (UV)
Used in food processing and hospitals to kill germ cells
Helps your body use vitamin D
XRAYS
Used for medicine. Allows doctors to see bone absorbed by x-rays, tissues do not

13. EM Spectrum…. Highest frequency
GAMMA RAYS
Produced in outer space
Radioactive substances and nuclear reactions produce gamma
Used for cancer treatment
Make EM Spectrum

14. 5. LIGHT Light energy comes from atoms absorbing energy
Light waves travel through space, but sound waves cannot!
Photons are bundles/packets of energy released as light. Light = Stream of Photons
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15. 6. REFLECTION
An image copies the object formed by reflected or refracted rays of light.
Regular & Diffuse reflection
Plane mirrors use regular reflection to create a virtual image
Left and right of the image is reversed
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16. 7. REFRACTION
Refraction – Bending of light due to a change in speed. Depends on medium.
Prisms – Glass that bends light. Different frequencies are bent different amounts & light is broken out into different colors.

17. Refraction (Cont.)

18. 8. Absorption
Waves are absorbed into solid objects, thus producing images in color.
Dark objects absorb ALL colors, whereas light color objects reflect most of the energy.