211.

The observed wavelength of light coming from a distant galaxy is found to be increased by 0.5% as compared with that coming from a
terrestrial source. The galaxy is

• stationary with respect to the earth

• approaching the earth with velocity of light

• receding from the earth with velocity of light

• receding from the earth with a velocity
  equal to 1.5 10⁶ m/s.

When a certain volume of water is subjected to 100 kPa pressure, the volume of water decreases by 0.005%. The speed of sound in water must be

• 140 m/s

• 300 m/s

• 1400 m/s

• 5000 m/s

A man stands in a narrow, steep-sided valley. When he shouts he hears two echoes, one after 1s and other after 2s.If the velocity of sound in air is 330 m/s, the width of the valley is

• 330 m

• 495 m

• 660 m

• 990 m

A cylindrical tube, open at both ends emits a fundamental frequency f in air. The tube is dipped vertically in water, so that half of it is in water. The fundamental frequency of air column is now

• f/2

• 3f/4

• f

• 2f

The end correction of a resonance column is 1.0 cm. If the shortest length resonating with the tuning fork is 15.0 cm, the next resonating length will be

• 31 cm

• 45 cm

• 46 cm

• 47 cm

A tuning fork A produces 4 beats/s with another tuning fork B of frequency 320 Hz. On filling one of the prongs of A, 4 beats/s are again heard when sounded with the same fork B. Then, the frequency of the fork A before the filling is

• 328 Hz

• 316 Hz

• 324 Hz

• 320 Hz

When the length of the vibrating segment of a sonometer wire is increased by 1%, the percentage change in its frequency is

• 100/101

• 99/100

• 1

• 2

The equation of a simple harmonic wave is given by $\mathrm{y} = 5 \sin \frac{\mathrm{\pi }}{2}(100\mathrm{t} - \mathrm{x})$ where x and y are in metre and time is in second. The period of the wave in second will be

• 0.04

• 0.01

• 1

• 5

The maximum particle velocity in a wave motion is half the wave velocity. Then the amplitude of the wave is equal to

• $\frac{\mathrm{\lambda }}{4\mathrm{\pi }}$

• $\frac{2\mathrm{\lambda }}{\mathrm{\pi }}$

• $\frac{\mathrm{\lambda }}{2\mathrm{\pi }}$

• λ

An engine moving towards a wall with a velocity 50 ms^-1 emits a note of 1.2 kHz. Speed of sound in air is 350  ms^-1 The frequency of the note after reflection from the wall as heard by the driver of the engine is

• 2.4 kHz

• 0.24 kHz

• 1.6 kHz

• 1.2 kHz