Page 1 - WORKSHEET -2 CH 15 CLASS XI

PHYSICS CLASS-11 CHAPTER 15(WAVES)

WORKSHEET -2 (STATIONARY WAVES)

1 A siren emitting a note of frequency n is fitted on a police van, traveling towards a stationary
listener. What is the velocity of the van, if the frequency of he note heard by the listener is
double the original frequency?
(a) V S  V

(b)
(c) V S  2V

(d)

2 Two tuning forks of frequencies 256 and 258 vibrations/second are sounded together. Then
the time interval between two consecutive maxima heard by an observer is (PMT - MP-88)
(a) 2 sec
(b) 0.5 sec
(c) 250 sec
(d) 252 sec

3 Two waves are y 1  0.25 sin 316t,
y 2  0.25 sin 310t are traveling in same direction. The number of beats produced per second
will be
(CPMT-93)
(a) 6
(b) 3

(c)
(d) 3

4 The transverse displacement of a string (clamped at its both ends) is given
by y (x,t) = 0.06 sin (2πx/3) cos (120πt). All the points on the string
between two consecutive nodes vibrate with
 (a) same frequency

 (b) same phase
 (c) same energy

 (d) different amplitude

5 A train, standing in a station yard, blows a whistle of frequency 400 Hz in
still air. The wind starts blowing in the direction from the yard to the station
with a speed of 10m/s. Given that the speed of sound in still air is 340 m/s,
 (a) the frequency of sound as heard by an observer standing on the
platform is 400 Hz.

 (b) the speed of sound for the observer standing on the platform is 350 m/s.