Free Printable Physics Unit 4 Test

1.

A closed organ pipe has fundamental frequency 100 Hz. What frequencies will be produced if its other end is also opened?

a)

200, 400, 600, 800,…..

b)

100, 300, 500, 700,……

c)

200, 300, 400, 500, …..

d)

100, 200, 300, 400,…….

2.

Two pipes, one is open, and other is closed at one end, having same length the ratio of their fundamental frequency is

a)

1 : 2

b)

2 : 1

c)

3 : 1

d)

4 : 1

3.

When the propagation of longitudinal wave through a material medium takes places, the quantities transmitted in the direction of propagation are

a)

Energy, momentum and mass

b)

Energy and mass

c)

Energy

d)

Energy and linear momentum

4.

Doppler shift in frequency does not depend upon

a)

The actual frequency of the wave

b)

The velocity of the source

c)

The distance of the source from the listener

d)

The velocity of the observer

5.

Four wires of identical lengths, diameters and materials are stretched on a sonometer box. The ratio of their tensions is 1 : 4 : 9 : 16. The ratio of their fundamental frequencies is

a)

16 : 9 : 4 : 1

b)

1 : 2 : 3 : 4

c)

4 : 3 : 2 : 1

d)

1 : 4 : 9 : 16

6.

An observer is moving towards a stationary source with a speed one fifth of the speed of sound. The frequency of sound heard by the observer will be if v is the speed and f is the original frequency of the sound waves

a)

$\frac{5}{6}f$

b)

$\frac{6}{5f}$

c)

$\frac{4f}{5}$

d)

$\frac{6f}{5}$

7.

A metallic wire of 2m length hooked between two points has tension of 10N. If mass per unit length of wire is 0.004 kg/s then fundamental frequency emitted by wire on vibration is:

a)

12.5 Hz

b)

24 Hz

c)

48 Hz

d)

6.25 Hz

8.

Any point on a string carrying a wave is moving with its maximum speed when:

a)

The magnitude of its acceleration is a maximum

b)

The magnitude of its displacement is a maximum

c)

The magnitude of its displacement is a minimum

d)

The magnitude of its displacement is half the amplitude

9.

A source of frequency f sends waves of wavelength λ traveling with speed v in some medium. If the frequency is changed from f to 2f, then the new wavelength and new speed are (respectively):

a)

2λ, v

b)

λ, 2v

c)

λ/2, v

d)

λ, v/2

10.

When both source and listener move in the same direction with a velocity equal to half the velocity of sound, the change in frequency of the sound as detected by the listener is:

a)

50%

b)

Zero

c)

25%

d)

None of these

11.

For destructive interference of sound waves the path difference between two interfering sounds should be

a)

$n\lambda$

b)

$\left(n+\frac{1}{2}\right)\lambda$

c)

Sometime n and sometimes $\left(n+\frac{1}{2}\right)\lambda$

d)

None of these

12.

The length of a simple pendulum executing simple harmonic motion is increased by 21%. The percentage increase in the time period of the pendulum of increases length is?

a)

50%

b)

21%

c)

30%

d)

10.5%

13.

The velocity of sound in open ended tube in 330m/s, the frequency of a wave is 1.1 kHz and length of the tube is 30cm, then number of harmonics that it will emit is?

a)

2

b)

3

c)

4

d)

5

14.

Standing waves are produced in 10m long stretched string. If the string vibrates in 5 segments and wave velocity is 20 ms–1. Its frequency is:

a)

2 Hz

b)

4 Hz

c)

5 Hz

d)

10 Hz

15.

The essential properties of a medium for the propagation of mechanical waves are

a)

Inertia and mass

b)

Inertia and elasticity

c)

Elasticity only

d)

Inertia only

16.

An observer moves towards a stationary source of sound, with a velocity one fifth of the velocity of sound. What is the percentage increase in the apparent frequency?

a)

Zero

b)

0.5%

c)

5%

d)

20%

17.

Doppler's effect will not be applicable when the velocity of sound source is

a)

Equal to that of the sound velocity

b)

Less than the velocity of sound

c)

Greater than the velocity of sound

d)

Zero

18.

Sound travels faster in moist air at STP because

a)

Moist air is heavier than dry air

b)

The pressure of moist air is greater than that of dry air

c)

The value of $\gamma$ of moist air is greater than that for dry air

d)

The density of moist air is less than that of dry air

19.

On decreasing the temperature, the frequency of an organ pipe becomes

a)

Decrease

b)

Equal

c)

Increase

d)

Infinity

20.

The speed of sound in the direction of wind relative to ground (where v is speed of sound and v_w is speed of wind)

a)

V

b)

V - V_w

c)

V + V_w

d)

V $\pm$ V_w

21.

The phase difference between the particles vibrating at two consecutive nodes is:

a)

Zero

b)

$\pi$

c)

$\frac{\pi}{2}$

d)

2 $\pi$

22.

The velocity of sound is generally greater is solids than in gases because

a)

The density of solids is high and the elasticity is low

b)

The density of solids is low and the elasticity is high

c)

Both the density and the elasticity of solids are very low

d)

The elasticity of solids is very high

23.

When water waves pore from shallow water into deep water how do the frequency, wave length and speed change:

a)

A

b)

B

c)

C

d)

D

24.

The figure represents a progressive wave travelling at a speed of 1250 ms^-1

The wavelength of the wave is:

a)

25 mm

b)

6.25 mm

c)

50 mm

d)

12.50 mm

25.

Two identical waves of same “f” moving towards the same destination such that both have an amplitude of 2 cm reaches at a point simultaneously. After the interference at that point the resultant wave emerges with an amplitude of 2 cm. for which value of phase difference it has happened?

a)

$\theta$ = 60°

b)

$\theta$ = 120°

c)

$\theta$ = 180°

d)

not possible

26.

The ratio of speed of sound in nitrogen gas to that in helium gas; at 300 K is:

a)

$\sqrt[]{\frac{2}{7}}$

b)

$\sqrt[]{\frac{1}{7}}$

c)

$\frac{\sqrt[]{3}}{5}$

d)

$\frac{\sqrt[]{16}}{5}$

27.

Ratio of isothermal modulus of elasticity to adiabatic modulus of elasticity is:

a)

$\gamma$

b)

$\sqrt[]{\gamma}$

c)

$\frac{1}{\gamma}$

d)

$\frac{1}{\sqrt[]{\gamma}}$

28.

The figure represents a progressive wave travelling at a speed of 1500 ms^-1.

The frequency of vibration of the particle is:

a)

50 kHz

b)

250 kHz

c)

100 kHz

d)

500 kHz

29.

For constructive interference of the sound waves the phase difference between waves can be:

a)

π,3π,5π,7π,9π……

b)

0π,1π,2π,3π,4π,5π….

c)

0π,1π,3π,5π,7π……

d)

0π,2π,4π,6π,8π…

30.

The frequency of sound emitted from a source in water is 400 Hz. If speed of sound in water is 1200 ms^-1 and in air is 350 ms^-1, then the frequency of sound heard above the surface of water is:

a)

400 Hz

b)

800 Hz

c)

1000 Hz

d)

1200 Hz

31.

The relation between phase difference and path difference is:

a)

$ϕ=\frac{2\pi x}{λ}$

b)

$ϕ=\frac{2\piλ}{x}$

c)

$ϕ=\frac{2\pi}{x}$

d)

$ϕ=\frac{2\pi}{λ}$

32.

If you set up seventh harmonic on a string fixed at both ends how many nodes and antinodes are set up in it?

a)

8, 7

b)

7, 7

c)

8, 9

d)

9, 8

33.

2^nd overtone of an open organ pipe resonates with 5th harmonics of a closed organ pipe. The ratio of their length will be:

a)

$\frac{2}{3}$

b)

$\frac{3}{2}$

c)

$\frac{6}{5}$

d)

$\frac{5}{6}$

34.

A simple harmonic oscillator has a time period of 0.5 seconds. Which equation relates its acceleration a with displacement x ?

a)

$a=-20x$

b)

$a=-(40\pi)x$

c)

$a=-(4\pi)^2x$

d)

$a=-(\pi/10)^2x$

35.

The displacement of a body performing S.H.M is x=0.86cos⁡(π/4)t, the amplitude of motion and frequency of oscillation will be:

a)

$0.43,0.125$

b)

$0.86,0.125$

c)

$1,0.125$

d)

$0.28,0.125.$

36.

The time taken by a simple harmonic oscillator to move from half of extreme to extreme position is:

a)

$\frac{T}{4}$

b)

$\frac{T}{6}$

c)

$\frac{T}{8}$

d)

$\frac{T}{12}$

37.

An observer is moving towards a stationary source of sound waves with constant velocity observer with passage of time?

a)

b)

c)

d)

38.

If a tunnel is bored through the center of the earth and a stone is dropped into it then the:

a)

Stone will stop at the center of the earth

b)

Stone will move out from other side of the tunnel

c)

Stone will perform simple harmonic motion

d)

None of these

39.

The displacement of particle executing S.H.M having initial phase of 90° in half of the time period, if the amplitude of its motion is “A”, will be?

a)

Zero

b)

A

c)

2A

d)

4A

40.

The wavelength of the fundamental mode of vibration of a closed end pipe is (where L is length of air column):

a)

L

b)

2L

c)

4L

d)

L/2

Physics Unit 4 Test

Total questions: 40

Worksheet time: 59mins

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