Physics

A human ear can detect sound having intensity as low as ________ which is also called threshold of hearing.

• a

• b

• c

• d

The unit used for sound intensity level is _________.

• A. W/m*2

• B. W

• C. W/m

• D. decibel

• a

• b

• c

• d

• a

• b

• c

• d

5. If sound source approaches towards stationary listener, apparent frequency of sound

• A. Increases

• B. Decreases

• C. Remain same

• D. Becomes negative

6. If source of sound approaches towards stationary observer, frequency change is due to

• A. Decrease in speed of sound wave

• B. Increase in speed of sound wave

• C. Decrease in wavelength

• D. Increase in wavelength

Suppose that a sound source is emitting waves uniformly in all directions. If you move to a point twice as far away from the source, the frequency of the sound will be

• A. Unchanged.

• B. Half as great.

• C. One-fourth as great.

• D. Twice as great.

8. As you are moving very quickly toward a speaker emitting a pure tone, which characteristics of the sound get larger?

• B. Amplitude

• A. Frequency

• C. Wavelength

• D. Period

9. A sound of 40 decibels is

• A. twice as intense as a sound of 20 decibels.

• B. four times as intense as a sound of 20 decibels.

• C. 10 times as intense as a sound of 20 decibels.

• D. 100 times as intense as a sound of 20 decibels.

10. If fundamental frequency f1 = 131 Hz , then frequency of third harmonic be_________.

• A. f1 = 131 Hz

• B. f3 = 393 Hz

• C. f2 = 262 Hz

• D. f4 = 524 Hz