1. Sound and Light
Chapter 12

2. Sound A longitudinal wave that spreads in all directions
Speed depends on medium
Solids and liquids = quick movement
Gasses = slower movement
Increase temperature = increase speed

3. Intensity Loudness of the sound Measured in decibels (dB)
Increase amplitude = increase energy = increase loudness = increase intensity
Increase distance = decrease intensity
Measured in decibels (dB)

4. Pitch Perceived loudness of a sound Depends on frequency
Increase frequency = increase pitch

5. Infrasound vs. Ultrasound
Frequency below 20 Hz
Hard for human to hear (too low)
Ultrasound
Frequency above 20,000 Hz
Hard for human to hear (too high)

6. Uses of Sound Sonar Sonogram Are these infrasound or ultrasound?
Sound Navigation and Ranging
Reflect sound waves to show distance
Sonogram
Echoes (reflections) of very high frequency sound waves
Can see inside animals
Are these infrasound or ultrasound?

7. Uses of Sound Musical Instruments
Produce sound by vibrating air, solids, and strings
Resonance helps produce the sound
One vibrating object causes another object to vibrate

8. Light Can be explained as waves Can be explained as particles
Electromagnetic waves
Spread in all directions
Used to explain most of the light we see
Can be explained as particles
A stream of tiny particles (photons) moving very quickly

9. Speed of Light Fastest in a vaccum Other speeds depend on the medium
3 x 108 m/s (186,000 mi/s)
Other speeds depend on the medium
Gas is the fastest, then water, then transparent solids

10. Intensity of Light Brightness of light
Increase energy = increase brightness = increase intensity
Increase distance = decrease intensity

11. Reflection of Light Smooth surfaces reflection light in one direction
In-coming wave
Incident wave
Out-going wave
Reflected wave
Flat surface

12. Law of Reflection
Angle of incidence is equal to the angle of reflection
Incident angle
Reflected angle
Flat surface

13. Reflections of Light Rough surfaces reflect light in many directions

14. Reflection of Light Mirrors can cause reflections to change
Curved mirrors create distortions (changes)
Convex = bulge out = stretch image
Concave = curve in = compress image

15. Reflections
Convex
Concave

16. Electromagnetic Spectrum
Light at all possible energies, frequencies, and wavelengths

17. Electromagnetic Spectrum

18. Bending of Light Light is made of all colors so it appears white
Can be bent through a prism to separate white light into all colors
Known as dispersion

19. Color of Objects Objects have color because of what is reflected
All light hits an object
White light hits
Some colors absorbed
Some colors reflected - this is the color you see