20.1. 20.2 20.3 20.4 Longitudinal Wave 20.5 Longitudinal Wave.

20.1

20.2

20.3

20.4

Longitudinal Wave

20.5

Longitudinal Wave

20.6

Bending of Sound Waves Ultra-Sound (high frequency)

20.7

Ultra-Sound (high frequency)

20.8

Natural Frequency Resonance

20.9

Resonance

20.10

Interference

Noise-canceling Earphones

20.11

AM, FM Radio

20.12

beats

20.13

-- Questions --

MULTIPLE CHOICE.

Choose the one alternative that best completes the statement or

answers the question.

20.14

1) Compressions and rarefactions are characteristic of A) longitudinal waves. B) transverse waves. C) both of these. D) neither of these.

2) A sound wave is a A) standing wave. B) shock wave. C) transverse wave. D) longitudinal wave. E) none of these.

20.15

3) The speed of a sound wave in air depends on A) its wavelength. B) the air temperature. C) its frequency. D) all of these. E) none of these.

4) Double the frequency of a sound and you halve its A) speed. B) amplitude. C) wavelength. D) all of these. E) none of these.

20.16

5) A 340-hertz sound wave travels at 340 m/s in air with a wavelength of A) 1 m. B) 10 m. C) 100 m. D) 1000 m. E) none of these.

6) When the handle of a tuning fork is held solidly against a table, the sound becomes louder and the time the fork keeps vibrating A) remains the same. B) becomes shorter. C) becomes longer.

20.17

7) Which type of radio wave produces the least static in a radio receiver? A) FM B) AM C) Both have equal amounts of static.

8) The wavelengths of sound that carry farther in air are relatively A) short. B) long. C) no difference.

20.18

9) When the speed of sound near the ground is greater than higher in the air, sound tends to be bent A) downward. B) upward.

10) An explosion occurs 34 km away. Since sound travels at 340 m/s, the time it takes for the sound to reach you is A) 0.1 second. B) 1 second. C) 10 seconds. D) 20 seconds. E) more than 20 seconds.

20.19

11) The phenomenon of beats results from sound A) reflection. B) refraction. C) interference. D) all of these. E) none of these.

12) The explanation for refraction must involve a change in A) speed. B) wavelength. C) frequency. D) all of these. E) none of these.

20.20

13) A 1056-hertz tuning fork is sounded at the same time a piano note is struck. You hear three beats per second. What is the frequency of the piano string?

A) 1053 hertz B) 1056 hertz C) 1059 hertz D) 2112 hertz E) not enough information given to determine

14) The least amount of energy is required to produce forced vibration in an object

A) below its natural frequency. B) above its natural frequency. C) at its natural frequency.

20.21

15) Double the frequency of sound and you also double its A) speed. B) wavelength. C) amplitude. D) all of these E) none of these.

16) Inhaling helium increases the pitch of your voice. The reason for this is that sound travels A) slower in helium than in air. B) the same speed in helium, but the wavelength is greater. C) faster in helium than in air.

20.22

-- Answers --

MULTIPLE CHOICE.

The one alternative that best completes the statement or

answers the question.

20.23

Chapter 20

1) Answer: A 2) Answer: D 3) Answer: B 4) Answer: C 5) Answer: A 6) Answer: B 7) Answer: A 8) Answer: B 9) Answer: B 10) Answer: E 11) Answer: C 12) Answer: A 13) Answer: E 14) Answer: C 15) Answer: E 16) Answer: C