The equation of a spherical progessive wave is :
1. y = a sin t
2. y = a sin (t - kr)
3. y = sin (t - kr)
4. y = sin (t - kr)
The equation Y = 0.02 sin(500t)cos(4.5x) represents :
1. progressive wave of frequency 250 Hz along the x-axis
2. a stationary wave of wavelength 1.4 m
3. a transverse progressive wave of amplitude 0.02 m
4. progressive wave of speed of about 350 m
The diagram below shows the propagation of a wave. Which points are in same phase?
1. F and G
2. C and E
3. B and G
4. B and F
A longitudinal wave is represented by x = x sin 2. The maximum particle velocity will be four times the wave velocity if :
1. =
2.
3.
4.
Two waves represented by y = asint and y = asin(t + ) with = are superposed at any point at a particular instant. The resultant amplitude is :
1. a
2. 4a
3. a
4. zero
Two wires W and W have the same radius r and respective densities and such that . They are joined together at the point O, as shown in the figure. The combination is used as a sonometer wire and kept under tension T. The point O is midway between the two bridges. When a stationary wave is set up in the composite wire, the joint is found to be a node. The ratio of the number of antinodes formed in W to W is :
1. 1 : 1
2. 1 : 2
3. 1 : 3
4. 4 : 1
A pipe open at both ends has a fundamental frequency f in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now :
1. 2f
2. f
3.
4.
In a standing wave formed as a result of reflection from a surface, the ratio of the amplitude at an antinode to that at node is x. The fraction of energy that is reflected is :
1.
2.
3.
4.
A stretched wire 60 cm long is vibrating with its fundamental frequency of 256 Hz. If the length of the wire is decreased to 15 cm and the tension remains the same. Then the fundamental frequency of the vibration of the wire will be :
1. 1024
2. 572
3. 256
4. 64
Two strings A and B, made of the same material, are stretched by the same tension. The radius of string A is double the radius of B. A transverse wave travels on A with speed and on B with speed . The ratio is :
1. 1/2
2. 2
3. 1/4
4. 4
41 forks are so arranged that each produces 5 beats per sec when sounded with its near fork. If the frequency of the last fork is double the frequency of the first fork, then the frequencies (in Hz) of the first and the last fork are respectively:
1. 200,400
2. 205,410
3. 195,390
4. 100,200
Three sound waves of equal amplitudes have frequencies . They superpose to give beats. The number of beats produced per second will be :
1. 3
2. 2
3. 1
4. 4
A band playing music at frequency f is moving towards a wall at a speed v. A motorist is following the band with a speed v. If v is the speed of sound, the expression for the beat frequency heard by the motorist is :
1. f
2. f
3. f
4. f
A sound source emits a frequency of 180 Hz when moving towards a rigid wall with speed 5 m/s and an observer starts moving away from the wall with speed 5 m/s. Both source and observer move on a straight line which is perpendicular to the wall. The number of beats per second heard by the observer will be [Speed of sound = 355 m/s] :
1. 5 beats/s
2. 10 beats/s
3. 6 beats/s
4. 8 beats/s
Two trains are moving towards each other with speeds of 20 m/s and 15 m/s relative to the ground. The first train sounds a whistle of frequncy 600 Hz. The frequency of the whistle heard by a passenger in the second train before the train meets, is (the speed of sound in air is 340 m/s)
1. 600 Hz
2. 585 Hz
3. 645 Hz
4. 666 Hz