Question

1. The frequency, which is audible to the human ear is _____

a) 50 k Hz b) 20 k Hz c) 15000 k Hz d) 10000 k Hz

2. The speed of sound is maximum in ____

a) solids b) liquids c) gases d) All of them

3. The persistence of hearing for human ear is _____

a) 1 s b) 0.01 s c) 0.1 s d) 2 s


II. Fill in the blanks:

4. Rapid to and fro motion of a particle about its mean position is called ____

5. If the longitudinal wave travels from south to north, the particles of the medium

would be vibrating to _____

6. The minimum distance required to hear an echo is _____

7. The waves created by earthquake is ____


III. Match the following:

8. Infrasonic - Compressions

9. Echo - 22 k Hz

10. Ultrasonic - 10 Hz

11. High pressure region - Ultrasonograph


PART – B

IV. Answer the following:

12. Define longitudinal waves.

13. Define particle velocity.

14. What are the laws of reflection of sound?

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Answer 1

Answer:

Speed of sound= wavelenth×frequency

when frequency is 20Hz

then wavelength=

20

344

=17.2m

when frequency is 20KHz

then wavelength=

20000

344

(20KHz = 20000Hz)

=0.0172m