1.

A astronaut can’t hear the explosion on the surface of the moon because (CPMT-78)

(a) Frequency of explosion is out of audible range            

(b) Temperature at that point is very low

(c) There is no medium on moon

(d) None of above

Answer: (c)

2.

Ultrasonic, infrasonic and Audible waves travel through a medium with speeds n_u, n_i, n_a respectively, then (CPMT-89)

(a) n_u, n_i, n_a are nearly equal                  

(b) n_{u ³} n_{a ³} n_i

(c) n_{u £} n_{a £} n_i                 

(d) n_{a £} n_u and n_u » n_i

Answer: (a)

3.

A tuning fork when sounded together with a tuning fork of frequency 256 emits two beats. On loading the tuning fork of frequency 256 Hz. The number of beats heard are one per second. the frequency of tuning fork is (NCERT-75)

(a) 257 Hz        

(b) 258 Hz

(c) 256 Hz        

(d) 254 Hz

Answer: (d)

4.

Sound travels 40 m during 20 vibrations its wavelength l is, (AFMC-PUNE 96)

(a) 0.5 m          

(b) 2 m

(c) 3 m             

(d) 4 m

Answer: (b)

5.

A sound wave ahs frequency 500 Hz and velocity 360

m/sec. what is the distance between two particles

having phase difference of 60° (NCERT-90, CPMT 90)

(a) 0.7 cm        

(b) 12.0 cm

(c) 70 cm                  

(d) 120.0 cm

Answer: (b)

6.

Two adjacent piano keys are struck simultaneously. The notes emitted by them have frequencies n₁ and n₂. the number of beats heard per second is (CPMT-74, 78)

(a)      

(b)

(c) (n₁ - n₂)      

(d) 2 (n₁ - n₂)

Answer: (c)

7.

Beats are produced when two sound waves given by

y₁ = A sin 200 pt and y₂ = A sing 210 pt are sounded together. How many beats are produced/sec?

(a) 3

(b) 4

(c) 5

(d) 6

Answer: (c)

8.

Two waves of same amplitude and frequency arrive at point simultaneously. The resultant amplitude is same as amplitude of each wave. So that initial phase difference of the two waves is (MHT CET 2001)

(a)                 

(b)

(c)               

(d)

Answer: (c)

9.

An astronaut can’t hear his companion at the surface of the moon because (CPMT-78)

(a) Produced frequencies are above the radio frequencies             

(b) There is no medium for sound propagation

(c) Temperature is too low during night and too high during day moon                   

(d) None of above

Answer: (b)

10.

Elastic waves in a solid are

(a) Only transverse                 

(b) Only longitudinal

(c) Either transverse or longitudinal                     

(d) Neither transverse nor longitudinal

Answer: (c)

11.

Which of the following statement is wrong

(NCERT-73)

(a) Changes in air temperature have no effect on the speed of sound                     

(b) Changes in air temperature have effect on the speed of sound.

(c) The speed of sound in water is lower then in air                     

(d) Both ‘a’ and ‘c’

Answer: (d)

12.

Which one of he following represents progressive wave (CBSE-94)

(a) y = A sin kx

(b) y = A sit t

(c) y = A cos (at - bx + c)

(d) none of these

Answer: (d)

13.

The velocity of sound in air is not affected by change in (CPMT 72)

(a) Moisture content of air                      

(b) Temperature of air

(c) Atmospheric pressure                       

(d) Composition of air

Answer: (c)

14.

Doppler effect is applicable for (AFMC PUNE-98)

(a) Sound wave

(b) Light waves

(c) None of above

(d) Both ‘a’ and ‘b’

Answer: (d)

15.

When a plane wave travels in a medium in the + X-direction, the displacement of the particle is given by

y (x, t) = 0.01 sin 2p (t - 0.1x) where y and x are measured in metres and t in seconds what is the wavelength of the wave? (NCERT-84)

(a) 0.1 m          

(b) 10.0 m

(c) 1 m             

(d) 100.0 m

Answer: (b)

16.

If amplitude of waves at distance r from a point source is A, then amplitude at a distance 2 r will be

(a) 2A              

(b) A

(c)                 

(d)

Answer: (c)

17.

If two tuning forks A and B are sounded together, they produce 4 beats per second. A is then slightly loaded with wax, they produce two beats when sounded again. The frequency of A is 256 Hz. The frequency of B will be  (CPMT-76)

(a) 250 Hz        

(b) 252 Hz

(c) 260 Hz        

(d) 262 Hz

Answer: (b)

18.

There are three sources of sound of equal intensity with frequencies 400, and 401 and 402 vibrations/sec. the number of beats heard per second is (MNR-80)

(a) 0

(b) 1

(c) 2

(d) 3

Answer: (b)

19.

The intensities of sound are in the ratio 1 : 16 for two waves of same frequency and traveling in same medium. Their amplitudes are in the ratio

(EAM CET 83)

(a) 1 : 4           

(b) 1 : 16

(c) 4 : 1           

(d) 1 : 2

Answer: (a)

20.

The waves produced in a vibrating tuning fork are

(a) Longitudinal in both the stem and the prongs              

(b) Transverse in both stem and the prongs

(c) Longitudinal in prongs and transverse in stem             

(d) Longitudinal in stem and transverse in prongs

Answer: (d)

21.

In a wave motion, the velocity of the wave (V) and the maximum particle velocity (V_P) are related as

(a)  

(b)

(c)  

(d)

Answer: (b)

22.

The equation of displacement of two waves are given as y₁ = 10 sinand

y₂ = 5 (sin 3p t + then, what is the ratio of their amplitudes (AIIMS-97)

(a) 1 : 2           

(b) 2 : 1

(c) 1 : 1           

(d) None

Answer: (c)

23.

A transverse wave described by the equation y = y₀

sin 2p. The maximum particle velocity is equal to four times the wave velocity. Then (IIT 84)

(a)        

(b)

(c) l = py₀         

(d) l = 2 py₀

Answer: (b)

24.

A tunning fork C is sound with another fork D of frequency 384 Hz gives 4 beats/sec. When C is filed, the beat frequency become 3 beates/sec, then original frequency of tunning fork K is (MHT-CET 2006)

(a) 388 Hz        

(b) 380 Hz

(c) 387 Hz        

(d) 381 Hz

Answer: (b)

25.

The phase difference between two points is . If the frequency of wave is 50 Hz. Then what is the distance between two points (Given n = 330 m/s)

(MHT CET 2004)

(a) 2.2 m          

(b) 1.1 m

(c) 0.6 m          

(d) 1.7 m

Answer: (b)