2000 Microsoft Clip Gallery CHAPTER 9 WAVES LIGHT

© 2000 Microsoft Clip Gallery CHAPTER 9: WAVES & LIGHT (& Sound) Waves carry energy from one place to another K. Wilkinson 2015 Adapted from D. L. Power, Revised 1/20/01

1. NATURE OF WAVES © 2000 Microsoft Clip Gallery n Wave – any disturbance that transfers energy from one place to another without transferring matter. n Types of Waves n 1. Mechanical Waves, which require a medium. n Transverse – moves up and down, examples are water and seismic waves. n Longitudinal – moves forward and backward, example is sound waves Label the parts of the wave

Nature of Waves… 2. Electromagnetic (EM) Waves, can travel through space! n Light, radio, micro, infrared, xray, ultraviolet and gamma Wave Interactions n *Absorption n Transmission n *Reflection n *Refraction n Diffraction n n CAN SOUND TRAVEL THROUGH SPACE?

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

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

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

4. ELECTROMAGNETIC SPECTRUM http: //missionscience. nasa. gov/ems. Video_0 © 2000 Microsoft Clip Gallery

EM Spectrum… Lowest Frequency 1. RADIO WAVES a. Modulation variation of amplitude or frequency when waves are broadcast b. AM – amplitude modulation 1. Carries audio for T. V. Broadcasts 2. Longer wavelength so can bend around hills c. FM – frequency modulation 1. Carries video for T. V. Broadcasts

EM Spectrum… Low Frequency 2. a. b. 3. a. 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

EM Spectrum…. 4. VISIBLE LIGHT a. Light we can see b. ROYGBIV – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet. n Largest to Smallest Wavelength.

EM Spectrum…. High Freq 5. 6. ULTRAVIOLET (UV) a. Used in food processing and hospitals to kill germ cells b. Helps your body use vitamin D XRAYS a. Used for medicine. Allows doctors to see bone absorbed by x-rays, tissues do not

EM Spectrum…. Highest frequency 6. GAMMA RAYS a. Produced in outer space b. Radioactive substances and nuclear reactions produce gamma c. Used for cancer treatment Make EM Spectrum

5. LIGHT n n Light energy comes from atoms absorbing energy n Light waves travel through space, but sound waves cannot! Photons are bundles/packets of energy released as light. Light = Stream of Photons © 2000 Microsoft Clip Gallery

6. REFLECTION n An image copies the object formed by reflected or refracted rays of light. n Regular & Diffuse reflection n Plane mirrors use regular reflection to create a virtual image n Left and right of the image is reversed © 2000 Microsoft Clip Gallery

7. REFRACTION n Refraction – Bending of light due to a change in speed. Depends on medium. n Prisms – Glass that bends light. Different frequencies are bent different amounts & light is broken out into different colors.

Refraction (Cont. )

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