#### 11th Standard Physics Waves English Medium Free Online Test One Mark Questions 2020 - 2021

11th Standard

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Physics

Time : 00:25:00 Hrs
Total Marks : 25

25 x 1 = 25
1. A student tunes his guitar by striking a 120 Hertz with a tuning fork, and simultaneously plays the 4th string on his guitar. By keen observation, he hears the amplitude of the combined sound oscillating thrice per second. Which of the following frequencies is the most likely the frequency of the 4th string on his guitar?.

(a)

130

(b)

117

(c)

110

(d)

120

2. A person standing between two parallel hills fires a gun and hears the first echo after t1 sec and the second echo after t2 sec. The distance between the two hills is

(a)

$\frac { v({ t }_{ 1 }-{ t }_{ 2 }) }{ 2 }$

(b)

$\frac { v\left( { t }_{ 1 }{ t }_{ 2 } \right) }{ 2({ t }_{ 1 }-{ t }_{ 2 }) }$

(c)

v (t1+t2)

(d)

$\frac { v({ t }_{ 1 }+{ t }_{ 2 }) }{ 2 }$

3. The displacement y of a wave travelling in the x direction is given by y= (2 x10 -3) sin (300t -2x+$\frac{\pi}{4}$), where x and y are measured in metres and t in second. The speed of the wave is

(a)

150 ms-1

(b)

300 ms-1

(c)

450 ms-1

(d)

600 ms-1

4. Which of the following represents a wave

(a)

(x - vt)3

(b)

x(x+vt)

(c)

$\frac{1}{x+vt}$

(d)

sin(x+vt)

5. Let y=$\frac{1}{1+x^2}$ at t = 0 s be the amplitude of the wave propagating in the positive x-direction. At t = 2 s, the amplitude of the wave propagating becomes

(a)

0.5m s-1

(b)

1.0m s-1

(c)

1.5m s-1

(d)

2.0m s-1

6. Sound waves of wavelength travelling in a medium with a speed of v m/s enter into the medium where its speed is 2 v m/s, wavelength of sound waes in the second medium is?

(a)

$\lambda$

(b)

$\frac{\lambda}{2}$

(c)

$2\lambda$

(d)

$4\lambda$

7. Change in temperature of the medium changes

(a)

frequency of sound waves

(b)

.amplitude of sound waves

(c)

wavelength of sound waves

(d)

loudness of sound waves

8. Which of the following statement are true for a stationary wave?

(a)

Every particle has a forced amplitude which is different from the amplitude of its nearest particle

(b)

All the particles cross their mean position at the same time

(c)

There is no transfer of energy across any plane

(d)

All the above

9. A wave travelling along the x-axis described by the equation y (x, t) = 0.005 cos ($\alpha x-\beta t$). of the wavelength and time period of the wave are 0.08 and 2.0s then and in appropriate units are

(a)

$\alpha=12.50 \pi;\ \beta=\frac{\pi}{2.0}$

(b)

$\alpha=25.00\pi;\ \beta=\overline \pi$

(c)

$\alpha=\frac{0.08}{\pi}\pi;\ \beta=\frac{2.0}{\pi}$

(d)

$\alpha=\frac{0.04}{\pi}\pi;\ \beta=\frac{4.0}{\pi}$

10. The equation of a simple harmonic wave is given y = 5 sin$\frac{\pi}{2}$(100 - x); Where x and y are in meter and time.is in secons. The period of the wave in second will be

(a)

0.04

(b)

0.01

(c)

1

(d)

5

11. Y1 = 4 sin(wt + kx), Y2 = -4 cos(wt + kx), the phase difference is

(a)

$\frac{\pi}{2}$

(b)

$\frac{3\pi}{2}$

(c)

$\pi$

(d)

Zero

12. A particle on the tough of a wave art any instant will come to the mean position after a time (7= time period)

(a)

$\frac{T}{2}$

(b)

$\frac{T}{4}$

(c)

T

(d)

2T

13. If an experment with sonometer, a tuning fork of frequency 256 Hz resonates with a length of 25cm and another tuning fork resonates with constants the frequency of the second tuning fork is

(a)

163.84 Hz

(b)

400 Hz

(c)

320 Hz

(d)

204.8 Hz

14. The fractional change in wavelength of light coming from a star is 0.014%. What is its velocity?

(a)

4.2 x 103 m/s

(b)

3.8 x 108 m/s

(c)

3.5 x 103 m/s

(d)

4.2 x 104 m/s

15. Mechanical Waves ________.

(a)

are longitudinal only

(b)

are transverse only

(c)

can be both longitudinal and transverse.

(d)

are neither longitudinal for transverse waves.

16. Sound travels fastest in _________.

(a)

Steel

(b)

air

(c)

water

(d)

vacuum

17. Choose the correct statement:

(a)

sound waves are transverse waves

(b)

sound travels fastest through vaouum.

(c)

sound travels faster in solids than in gases.

(d)

sound travels faster in gases than in liquids

18. The speed of the wave represented by y =A sin(ωt - kx) is ________.

(a)

k/ω

(b)

ω/k

(c)

ωk

(d)

1/ωk

19. A wave of frequency 500 Hz has a velocity 300 m/s. The distance between two nearest points which are 60° out of phase, is _______

(a)

0.2 m

(b)

0.1 m

(c)

0.4 m

(d)

0.5 m

20. The equation of a wave is y = 4 sin $\left\{ \frac { \pi }{ 2 } \left( 2t+\frac { x }{ 8 } \right) \right\}$where y, x are in em and t in seconds. The amplitude wavelength, velocity and frequency of the wave are, respectively _________.

(a)

4 cm, 32 cm, 16 cm/s, 0.5 Hz

(b)

8 cm, 16 cm, 32 cm/s, 1.0 Hz

(c)

4 cm, 32 cm, 32 cm/s, 0.5 Hz

(d)

8 cm, 16 cm, 16 cm/s, 1.0 Hz

21. With the rise of temperature, the speed of sound in a gas ________.

(a)

increases

(b)

decreases

(c)

remain the same

(d)

may increase or decrease depending on the corresponding change in pressure.

22. The velocity of sound in are is not affected by change in the ________.

(a)

atmospheric pressure

(b)

moisture content of air

(c)

temperature of air

(d)

composition of air

23. If the amplitude of sound is doubled and the frequency reduced to one-fourth, the intensity will _________.

(a)

increase by a factor of 2

(b)

decrease by a factor of 2

(c)

decrease by a factor of 4

(d)

remain unchanged

24. The temperature at which the speed of sound in air becomes double its value at 27°C is________.

(a)

54°C

(b)

327°C

(c)

927°C

(d)

-123°C

25. When sound waves travel from air to water, which of the following remains constant?

(a)

velocity

(b)

frequency

(c)

wave length

(d)

all of these