**LEVEL – I **

1. The amplitude of resulting wave dues to superposition of y_{1} = A sin (ωt − kx) &

y_{2} = A sin (ωt − kx + δ) is

(A) 2A cos δ

(B) 2A tan (δ/2)

(C) A cos δ sin δ

(D) none

2. A sine wave has an amplitude A and wavelength λ . The ratio of particle velocity and the wave velocity is equal to ( 2πA = λ )

(A) ≤ 1

(B) = 1

(C) ≥ 1

(D) data insufficient.

3. The equation of a wave pulse moving with a speed 1 m/sec at time t = 0 is given as

y = f(x) = 1/(1 + x^{2}) . Its equation at time t = 1 second can be given as

(A)

(B)

(C)

(D)

4. The velocity of a transverse wave in a string does not depend on

(A) tension

(B) density of material of string

(C) radius of string

(D) length of string

5. The frequency of a tuning fork with an amplitude A = 1 cm is 250 Hz. The maximum velocity of any particle in air is equal to

(A) 2.5 m/s

(B) 5 π m/s

(C) 3.30 /π m/sec

(D) none of these

6. In a resonance column experiment, the first resonance is obtained when the level of the water in tube is 20 cm from the open end. Resonance will also be obtained when the water level is at a distance of

(A) 40 cm from the open end.

(B) 60 cm from the open end.

(C) 80 cm from the open end.

(D) data insufficient.

7. A wire of length l having tension T and radius r vibrates with natural frequency f. Another wire of same metal with length 2l having tension 2T and radius 2r will vibrate with natural frequency

(A) f

(B) 2f

(C) 2√2 f

(D) f /2√2

8. Under the same conditions of pressure and temperature, the velocity of sound in oxygen and hydrogen gases are v_{o} and v_{H} , then

(A) v_{H} = v_{o}

(B) v_{H} = 4v_{o}

(C) v_{o} = 4 V_{H}

(D) v_{H} = 16 v_{o}

9. A tuning for of frequency 600 Hz produces a progressive travelling wave having wave velocity 300 m/s. Two particles of a medium, separated by 1.5 m, vibrate being affected by the wave (A) in phase

(B) in opposite phase.

(C) 45° out of phase.

(D) none of these

10. At t = 0 source starts falling under gravity and a detector is projected upwards with a velocity 10 m/s. For the vertical upward motion of detector

(A) apparent frequency received by detector = source frequency.

(B) initially apparent frequency > source frequency and finally less than source frequency.

(C) apparent frequency depends only on the detector velocity.

(D) date insufficient.

__Answers:__

**1.(D) 2. (A) 3. (B) 4. (D) 5. (B) 6. (B) 7. (D) 8. (B) 9. (A) 10.(B) **