CBSE
Multiple Choice QuestionsA wave packet with center frequency ω is propagating in dispersive medium with phase velocity of 1.5 x 103 m/s. When the frequency ω is increased by 2%, the phase velocity is found to decrease by 3 %. What is group velocity of the wave packet?
0.25 × 103 m/s
1.0 × 103 m/s
0.6 × 103 m/s
0.75 × 103 m/s
When a stretched wire and a tuning fork are sounded together, 5 beats per second are produced, when length of wire is 95 cm or 100 cm, frequency of the fork is
90 Hz
100 Hz
105 Hz
195 Hz
Figure shows spring + block + pulley system which are light. The time period of mass would be
Linear density of a string of is 1.3 x 10-4 kg/m and wave equation is y = 0.021 sin (x + 30t ), Find, the tension in the string where, x in metre and t in second
0.12 N
0.21 N
1.2 N
0.012 N
A bat emitting an ultrasonic wave of frequency 4.5 x 10' Hz at speed of 6 m/s between two parallel walls. The two frequencies heared by the bat will be
4.67 x 104 Hz, 4.34 x 104 Hz
4.34 x 104 Hz, 4.67 x 104 Hz
4.5 x 104 Hz, 5.4 x 104 Hz
4.67 x 103 Hz, 4.34 x 104 Hz
A sound source producing waves of frequency 300 Hz and wavelength lm observer is stationary, while source is going away with the velocity 30 m is, then apparent frequency heared by the observer is
270 Hz
273 Hz
383 Hz
300Hz
When an open organ is dipped in water upto half of its height, then its frequency will become
half
double
remain same
four time
A 4 kg block is suspended from the ceiling of an elevator through a spring having a linear mass density of 19.2 x 10-3 kg m-3 . Find the speed with respect to spring with which a wave pulse can proceed on the spring if the elevator accelerates up at the rate of 2.0 ms-2.
Take g = 10 ms-2
30 m/s
42 m/s
46 m/s
50 m/s
An observer is approaching with velocity v towards a light source. If the velocity of light is c, then velocity of light with respect to observer will be
c - v
c
c + v
A transverse wave is represented by the equation . For what value of is the particle velocity equal to two times the wave velocity
