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Explain how the Doppler effect is used by the police to measure the speed of a car.

Complete the following exercises.
1. What is the source of all waves?

2. A water wave vibrates up and down four times each second, the distance between two successive crests is 5 meters, and the height from the lowest part to the highest part of the wave is 2 meters.
a. What is the frequency of the wave in hertz?
b. What is the period of the wave in seconds?
c. What is the speed of the wave in meters per seconds?
d. What is the amplitude of the wave in meters?

3. When you sit in the stands at a baseball stadium, you will hear the crack of the bat a short time after you see the batter hit the ball. Explain.

4. Why is the moon sometimes described as silent?

5. You are hiking in a canyon and you notice an echo. You decide to let put a yell and notice it took 2 seconds before you heard the echo of your yell. How far away is the canyon wall that reflected your yell?

6. Explain how the Doppler effect is used by the police to measure the speed of a car.

7. The light from the sun has higher frequencies from one side of the sun than from the other side. What does that tell you about the sun?

8. What is the source of all electromagnetic waves?

9. Why is the lettering on the front of an ambulance “backwards” (see figure below)?

10. What do radio waves, microwaves, light, and x-rays have in common?

11. Rank the following electromagnetic waves in order of increasing frequency.
A. Microwaves
B. Radio waves
C. Ultraviolet radiation
D. Visible light
E. X-rays
F. Infrared radiation

12. During a lunar eclipse the moon is in the shadow of the Earth. Why does the moon have a faint red color during the eclipse?

13. The distance from the sun to the Earth is 1.5 x 1011 m. How long does it take for light from the sun to reach the earth? Give your answer in seconds.

14. Why are polarized sunglasses particularly effective in reducing glare?

15. Match the following colored objects with the way in which the colors are produced.
1) Red rose
2) Rainbow
3) Oil film
4) Peacock feather
5) Blue sky

A. Scattering
B. Refraction
C. Diffraction
D. Interference
E. Selective reflection

The remaining questions are multiple-choice questions:

16. If the frequency of a vibration is doubled, what happens to the period?
A. The period is doubled.
B. The period remains the same.
C. The period is reduced to one-quarter.
D. The period is reduced to one-half
E. The period is quadrupled.

17. What is the distance between two successive crests on a transverse wave called?
A. Wavelength
B. Period
C. Amplitude
D. Frequency
E. Compression

18. Noise-cancelling earphones use which of the following phenomena?
A. Frequency
B. Constructive interference
C. Destructive interference
D. Resonance
E. Beats

19. If the sun were to suddenly “turn off’, we would not know about it for about 8 minutes. Why?
A. It would take about 8 minutes to realize what happened because of the darkness.
B. It takes about 8 minutes for the sun to “power down”.
C. It takes about 8 minutes for Earth to spin around so we can see the sun.
D. It takes about 8 minutes for the light to travel from the sun to Earth.

20. If the atmosphere was much thicker than it is now, how would the sun appear?
A. The sun would appear the same.
B. The sun would appear blue-violet.
C. The sun would appear green-blue.
D. The sun would appear red-orange.
E. The sun would appear yellow-green.

21. If you dip your finger in a tub of water at a constant rate, concentric circular waves with a constant spacing (wavelength) will form. If you double the frequency at which you dip your finger, what will happen to the wavelength?
A. The wavelength is reduced to one-quarter.
B. The wavelength is reduced to one-half.
C. The wavelength is quadrupled.
D. The wavelength is doubled.
E. The wavelength remains the same.

22. If you hear the clap of a thunder 5 seconds after seeing the flash of lightning, how far away from you did the lightning strike?
A. About 5 miles
B. About 5 kilometers
C. About 1 mile
D. About 1 kilometer

23. What are the three paint colors used for color subtraction?
A. Red, yellow, and blue
B. Red, green, and blue
C. Orange, purple, and green
D. Magenta, green, and yellow
E. Magenta, cyan, and yellow

24. If you shine a beam of red light and a beam of green light on the same area of a screen, what color will you see on the screen?
A. Red
B. Green
C. White
D. Yellow
E. Cyan
F. Magenta

25. If you mix equal amounts of cyan pigments and magenta pigments on a sheet of white paper, what color will you see on the paper?
A. Red
B. Blue
C. Black
D. Yellow
E. Cyan
F. Magenta

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