Waves CBSE Questions & Answers

Waves

This is Physics Class 11 Waves CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Velocity of sound in air is 300 m/s. Then the distance between two successive nodes of a stationary wave of frequency 1000 Hz is.
  • A
    15 cm
    Correct
  • B
    20cm
  • C
    10 cm
  • D
    30cm
2
There are three sources of sound of equal intensities with frequencies 400, 401 and 402 Hz. The number of beats per seconds is
  • A
    3
  • B
    1.0
    Correct
  • C
    2
  • D
    0
3
The velocity of sound in gas in which two waves of wavelength 1.0 m and 0.01 m produces 4 beats/sec. is
  • A
    440 m/s
  • B
    1010 m/s
  • C
    404 m/s
    Correct
  • D
    360 m/s
4
A fork of unknown frequency when sounded with another fork of frequency 256 Hz produces 4 beats/sec. The first fork is loaded with wax. It again produces 4 beats/sec. When sounded together with the fork of 256 Hz frequency, then the frequency of first tuning fork is
  • A
    252 or 260 Hz
  • B
    252 Hz
  • C
    None of these
  • D
    260Hz
    Correct
5
Two tuning forks of frequencies 250 Hz produce beats. If a maximum is produced just now, after how much time the minimum is produced at the same place
  • A
    \({1 \over 6}s\)
  • B
    \({1 \over {18}}s\)
    Correct
  • C
    \({1 \over {12}}s\)
  • D
    \({1 \over {24}}s\)
6
56 tuning forks are arranged in a series that each fork gives 4 beats/sec, with the previous one. The frequency of last fork is 3 times that of first. Then frequency of first fork is
  • A
    110 Hz
    Correct
  • B
    52 Hz
  • C
    60 Hz
  • D
    56 Hz
7
A tuning fork produces 4 beats/sec. with 50 cm and 40 cm of a stretched wire, of a sonometer. The frequency of fork is
  • A
    90 Hz
  • B
    36 Hz
    Correct
  • C
    50 Hz
  • D
    110 Hz
8
Two waves represented by \({{\rm{Y}}_{\rm{1}}}\) = \({{\rm{a}}_{\rm{1}}}\) sin wt and \({{\rm{Y}}_{\rm{2}}}\) = \({{\rm{a}}_{\rm{2}}}\) cos wt are superimposed at a point at a particular instant. The amplitude of resultant wave is
  • A
    \(\sqrt {a_1^2 - a_2^2} \)
  • B
    \(\sqrt {a_1^2 + a_2^2} \)
    Correct
  • C
    \({a_1} + {a_2}\)
  • D
    \({a_1} - {a_2}\)
9
The fundamental frequency of an open pipe is N keeping the pipe vertical. It is submerged in water so that half of its length is filled with water. The fundamental frequency of air column is
  • A
    2N
  • B
    N
    Correct
  • C
    N/2
  • D
    3N/4
10
If a star emitting orange light moves away from the earth, its color will
  • A
    turns gradually blue
  • B
    appear red
    Correct
  • C
    remain the same
  • D
    appear yellow
11
A tuning fork of frequency 500 Hz is sounded on a resonance tube. The first & second resonances are obtained at 17 cm and 52 cm. The velocity of sound in m/s is
  • A
    520
  • B
    170
  • C
    350.0
    Correct
  • D
    850
12
A whistling engine is approaching a stationary observer with velocity 110m/s. The velocity of sound is 330 m/s. The ratio of frequencies as heard by observer at the time of approaching and passing of engine is
  • A
    it is 2:1
    Correct
  • B
    it is 3:6
  • C
    it is 4:1
  • D
    it is 4:3
13
When a wave undergoes reflection at rarer medium then it undergoes a phase difference of
  • A
    \(\pi \) /4
  • B
    \(\pi \) /2
  • C
    No change in phase
    Correct
  • D
    \(\pi \)
14
The frequency of the third harmonic of a closed organ pipe is equal to which of the overtones?
  • A
    second
  • B
    none of above
  • C
    first
    Correct
  • D
    third
15
A stretched string fixed at both ends has n nodes then the length of string in terms of wavelength is
  • A
    (n - 1) \({\lambda \over 2}\)
    Correct
  • B
    n \({\lambda \over 2}\)
  • C
    (2n - 1) \({\lambda \over 2}\)
  • D
    (n + 1) \({\lambda \over 2}\)