#### Acoustics English Medium Free Online Test 1 Mark Questions 2020-2021

10th Standard

Reg.No. :
•
•
•
•
•
•

Science

Time : 00:15:00 Hrs
Total Marks : 15

Part A

15 x 1 = 15
1. The sound waves are reflected from an obstacle into the same medium from which they were incident. Which of the following changes?

(a)

speed

(b)

frequency

(c)

wavelength

(d)

none of these

2. The velocity of sound is affected by

(a)

temperature

(b)

density

(c)

pressure

(d)

all the above

3. A sound wave passes through gold rod and comes into the surrounding air. What is the relation between original wavelength A and new wavelength λ'?

(a)

λ=λ'

(b)

λ>λ'

(c)

λ<λ'

(d)

None of the above

4. A car playing music at a frequency of 250 Hz moves at 20 m/s towards an observer that has frequency. What frequency the observer can hear when
(i) it approaches and
(ii) when it passes by?

(a)

approaching: $250\times \left( \frac { v+20 }{ v } \right) ;$
leaving: $\\ 250\times \left( \frac { v-20 }{ v } \right)$

(b)

approaching: $\\ 250\times \left( \frac { v }{ v+20 } \right) ;$
leaving: $250\times \left( \frac { v }{ v-20 } \right)$

(c)

approaching:$250\times \left( \frac { v-20 }{ v } \right) ;$
leaving: $250\times \left( \frac { v+20 }{ v } \right)$

(d)

approaching: $250\times \left( \frac { v }{ v-20 } \right) ;$
leaving: $250\times \left( \frac { v }{ v+20 } \right)$

5. Infrasound can be heard or produced by

(a)

dog

(b)

bat

(c)

rhinoceros

(d)

human beings

6. The pitch of sound depends on

(a)

frequency

(b)

amplitude

(c)

both

(d)

none

7. The region of increased pressure in a wave is called

(a)

crest

(b)

through

(c)

compression

(d)

particle

8. Sound travels with a speed of 330 ms-1. What is the wavelength of sound whose frequency is 550 Hz?

(a)

0.6 m

(b)

0.7 m

(c)

0.4 m

(d)

0.2 m

9. Sound travels with a velocity of ____________ in dry air

(a)

332 ms-1

(b)

330 ms-1

(c)

331 ms-1

(d)

336 ms-1

10. Sound propagates maximum in

(a)

gas

(b)

liquid

(c)

solid

(d)

all

11. Bats deflect from the obstacles in their path by receiving the reflected _______ waves.

(a)

(b)

ultrasonic

(c)

electromagnetic

(d)

infrasonic

12. When sound travels through air, the air particles.

(a)

do not vibrate

(b)

vibrate but not in any fixed direction

(c)

vibrate perpendicular to the direction of wave propagation

(d)

vibrate along the direction of wave propagation

13. Sound waves do not travel through.

(a)

vaccum

(b)

solid

(c)

liquid

(d)

gases

14. The speed of sound in a medium depends upon

(a)

frequency

(b)

amplitude

(c)

wavelength

(d)

properties of the medium

15. What does it mean when a wave's amplitude increases?

(a)

Its frequency also increases

(b)

It is moving in denser medium

(c)

Its wavelength gets longer

(d)

It carries more energy