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Class 8

Explore popular questions from Sound for Class 8. This collection covers Sound previous year Class 8 questions hand picked by experienced teachers.

Sound

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Q 1. Eardrum is a part of:

A

Sound producing organ

B

Skeletal system

Hearing organ

D

Reproductive organ.

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Q 2. The hearing range of human ear is:

20 Hz to 20,000 Hz.

B

Less than 20 Hz.

C

More than 20,000 Hz .

D

20 Hz to 25,000 Hz.

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Q 3. The pitch of sound depends on:

Frequency

B

Amplitude

C

Both of these

D

None of these.

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Q 4. To and fro motion of an object is called

A

waves

B

amplitude

vibration

D

all of above

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Q 5. The transfer of energy in a material medium due to the periodic motion of its particles is called

wave motion

B

stream

C

pulse

D

none of the above

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Q 6. A pulse is a wave :

A

of long duration

of short duration

C

both (A) and (B)

D

none of these

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Q 7. Sound waves cannot pass through :

A

a solid liquid mixture

B

a liquid gas mixture

C

an ideal gas

a perfect vacuum

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Q 8. In a sound wave, the direction of propagation is :

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 vibrations of the vibrating body

D

at an angle of 60° to the direction of vibrations of the vibrating body

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Q 9. The product of time period and frequency is :

A

0

1

C

infinite

D

0 or 1

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Q 10. Time period of a sound wave having the wavelength 0.2 m and frequency 10Hz will be :

A

2 s

B

0.2 s

0.1 s

D

0.02 s

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Q 11. Echo is a type of :

reflected sound

B

refracted sound

C

polarized sound

D

none of these

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Q 12. The speed of sound in air at 0°C is approximately:

332 ms{tex}^{-1}{/tex}

B

350 ms{tex}^{-1}{/tex}

C

530 ms{tex}^{-1}{/tex}

D

332 kms{tex}^{-1}{/tex}

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Q 13. Mark the correct options according to terms in column I and column II

Column I Column II
(1) high pitch (p) Faint sound
(2) low pitch (q) Loud sound
(3) small amplitude (r) High frequency
(4) large amplitude (s) Low frequency

(1)- r, (2)-s, (3)-p, (4)-q

B

(1)-r, (2)-p, (3)-r, (4)-q

C

(1)-s, (2)-q, (3)-r, (4)-P

D

(1)-p, (2)-s, (3)-r, (4)-q

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Q 14. A thunder clap is heard 5.5 second after the lightning flash. The distance of the flash is : (speed of sound in air is 340 m/s)

A

1780 m

1870m

C

300 m

D

3560 m

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Q 15. A source produces 50 crests and 50 troughs in 0.5 s. What is the frequency of the wave?

100 Hz

B

150 Hz

C

50 Hz

D

125 Hz

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Q 16. The wavelength of sound in air is 5 cm. Its frequency is (Take velocity of sound = 330 m/s) :

6.6 kilo cycles per second

B

660 cycles per second

C

6.6 mega cycles per second

D

6 × 10{tex}^9{/tex} cycles per second

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Q 17. A sonar device on a submarine sends out a signal and receives an echo 5 s later. Calculate the speed of sound in water if the distance of the object from the submarine is 3625 m :

A

1550 ms{tex}^{-1}{/tex}

1450 ms{tex}^{-1}{/tex}

C

3000 ms{tex}^{-1}{/tex}

D

3625 ms{tex}^{-1}{/tex}

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Q 18. A wave completes 20 vibrations in 2.5 s. Its frequency is

A

20 Hz

8 Hz

C

200 Hz

D

50 Hz

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Q 19. A scientist performed an experiment as shown in the figure. What happened when air was pumped out of the jar completely and he rang the bell ?

A

The sound became louder

B

The sound became fainter first and then louder once all the air was pumped out

The sound could not be heard anymore

D

The sound was the same as before

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Q 20. Which of the following is/are correct ?
(A)Besides helping in finding distance of an object, SONAR also indicates its range
(B)Megaphone is a device which works on the principle of reflection of sound
(C)Ultrasonics are used to detect earthquakes
(D)Like light, sound waves also obey laws of reflection.

A

B, C and D

B

A, B and C

A, B and D

D

A, C and D

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Q 21. Sonic vibrations were sent down from a ship return after 2 seconds. What is the depth of the sea, if the speed of sound in water is 1.5 km s{tex}^{-1}{/tex} ?

A

150 m

B

3 km

1.5 km

D

750 m

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Q 22. In an experiment to measure the speed of sound in air, a boy stands 40 m from a wall and bangs two pieces of wood together. At the instant he hears the echo, he bangs them together again. He does this activity 50 times. The time taken for 50 bangs is 12 s. Which calculation gives the speed of sound in air ?

A

{tex}\frac{12}{40\times50}{/tex}

B

{tex}\frac{40\times50}{12}{/tex}

{tex}\frac{40\times 2 \times50}{12}{/tex}

D

{tex}\frac{40\times 2 \times12}{50}{/tex}

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Q 23. Shweta observes lightning in her area. She hears the sound 5 s after the observed lighting. How far is she from the place where lightning occurs if speed of sound in air is 330 m s{tex}^{-1}{/tex}

1.65 km

B

2.55 km

C

3.65 km

D

4.55 km

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Q 24. While playing a violin, in which of the following the vibrations can take place ?

A

The wire only

B

Air only

C

The box only

Both the wire and box

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Q 25. Bees which are not carrying honey fly with a flapping frequency of 440 Hz while those which are carrying honey fly with a flapping frequency of 300 Hz. The sound made by bees which are not carrying honey has :

A

A lower pitch

A higher pitch

C

A smaller loudness

D

A greater loudness