# CBSE Worksheet for Chapter - 4 Sound Wave Class 8

## Find CBSE Worksheet for chapter-4 Sound Wave class 8

CLASS-8

BOARD: CBSE

PHYSICS Worksheet - 4

TOPIC: Sound Wave

For other  CBSE Worksheet for class 8 Science  check out main page of Physics Wallah.

#### SUMMARY

• Wave motion, Classification of waves, Sound wave and its characteristics

• Range of hearing, Speed of sound in different medium

• Effect of temperature on speed of sound, Audible, Ultrasonic and Infrasonic waves

• Reflection of sound, Echo, Noise

• Hearing impairment and measure of intensity of sound

• Human ear

#### SECTION 1 – OBJECTIVE

1. The unit of that quantity on which pitch of the sound depends is:

(A) Hertz

(B) meter

(C) meter/second

(D) second

2. The unit of that quantity on which loudness of sound depends is:

(A) Hertz

(B) meter

(C) meter/second

(D) second

3. Sound travels

(A) Faster in solids than gases

(B) Faster in gases than liquids

(C) Faster in vacuum, than anything else

(D) Faster in liquids than solids

4. Sound is produced by

(A) A body at rest

(B) a body moving with a uniform velocity

(C) a body moving with constant acceleration

(D) a vibrating body

5. In the sound waves _________ are formed

(A) Crests and troughs

(B) nodes and antinodes

(C) Compression and rarefactions

(D) none of the above

6. In a sound wave, the direction of propagation is:

(A) In the direction of the vibrations of the vibrating body

(B) Opposite to the direction of vibrations of vibrating body

(C) Perpendicular to the direction of vibration of the vibrating body

(D) At an angle of 60° to the direction of vibrating of the vibrating body

7. With the rise of temperature, the velocity of sound

(A) Decreases

(B) Increases

(C) Remains the same

(D) Is independent of temperature

8. Human ear can hear

(A) Audible sound

(B) Infra sound

(C) Ultra sound

(D) All of the above

9. Sound of frequency below 20 Hz is called :

(A) Infrasonic

(B) ultrasonic

(C) Supersonic

(D) none of the above

10. The property which is common to both light waves and sound waves is that:

(A) Both are electromagnetic waves

(B) Both are reflected by surfaces

(C) Direction of propagation is perpendicular to the direction of vibration of the particles of the medium

(D) Both need a material medium to travel from one place to another

11. The speed of wave is 340 ms-1. What is the wavelength of the wave if its frequency is 500Hz

(A) 0.68m

(B) 6.8m

(C) 68m

(D) 0.68cm

12. Middle ear consists of ……….. bones.

(A) 1

(B) 2

(C) 3

(D) 4

#### SECTION 2 – SUBJECTIVE

1. Define the following physical quantities related to sound waves:

(A) Pitch

(B) Loudness and softness

(C) Intensity

(D) Quality

2. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency

3. Describe the working of human hear with a neat and labelled diagram?

4. A bat emits ultrasonic sound of frequency 100 kHz in air. If this sound meets a water surface, what is the wavelength of

(a) the reflected sound,

(b) the transmitted sound?

Speed of sound in air = 340ms-1 and in water=1486 ms-1.

5. A sonar device on a submarine sends out a signal towards an object in water and receives an echo 5s later, calculate the speed of sound in water if the distance of the object from the submarine is 3625m?

### Solutions: to worksheet-4 Topic- Sound Wave

 1. A 2. b 3. A 4. d 5. C 6. A 7. B 8. A 9. A 10. B 11. A 11. C

#### SUBJECTIVE

3. 0.15, 10 H3

4. (I) 3.4 X 10-3 M (II) 1.49 X 10-2M

5. 1450