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16 questions · 1 auto-graded MCQ + 15 self-marked written.

Question 11 Mark
Two sound waves having a phase difference of 60° have path difference of _______.
Answer
Two sound waves having a phase difference of 60° have path difference of $\frac{\lambda}{6}$.
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MCQ 21 Mark
A point source emits sound equally in all directions in a non$-$absorbing medium. Two points $P$ and $Q$ are at distances of $2m$ and $3m$ respectively from the source. The ratio of the intensities of the waves at $P$ and $Q$ is:
  • A
    $3 : 2$
  • B
    $2 : 3$
  • $9 : 4$
  • D
    $4 : 9$
Answer
Correct option: C.
$9 : 4$
Here, $r_1 = 2m$ and $r_2 = 3m$
$\text{I}\propto\frac{1}{\text{r}^2}$
$\therefore \frac{\text{I}_1}{\text{I}_2}=\frac{\text{r}^2_2}{\text{r}^2_1}=\frac{3^2}{2^2}=\frac{9}{4}$
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Question 31 Mark
Source of sound and observer are moving towards each other the observer will hear ______ frequency.
Answer
Source of sound and observer are moving towards each other the observer will hear higher frequency.
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Question 41 Mark
Newton's formula for velocity of sound in gases is _______.
Answer
Newton's formula for velocity of sound in gases is $\text{v}=\sqrt{\frac{\text{P}}{\rho}}$.
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Question 51 Mark
Apparent change in frequency of sound waves when source of sound and listener are in relative motion is known as ______.
Answer
Apparent change in frequency of sound waves when source of sound and listener are in relative motion is known as doppler effect.
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Question 61 Mark
Standing waves are formed on a string when interference occurs between two waves having _______.
Answer
Standing waves are formed on a string when interference occurs between two waves having same amplitude and travelling.
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Question 71 Mark
The frequency of vibrating air column in closed organ pipe is n, if its length be doubled and radius halved, its frequency will be nearly _______.
Answer
The frequency of vibrating air column in closed organ pipe is n, if its length be doubled and radius halved, its frequency will be nearly $\frac{\text{n}}{2}.$
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Question 81 Mark
The waves produced by a motor boat sailing in water are ______.
Answer
The waves produced by a motor boat sailing in water are transverse waves.
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Question 91 Mark
Mechanical waves require a mechanical medium to propagate. Properties of medium required for mechanical wave propagation is ________ and _________.
Answer
Mechanical waves require a mechanical medium to propagate. Properties of medium required for mechanical wave propagation is inertia and elasticity.
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Question 101 Mark
The loudness and pitch of a sound note depends on _____ and _____.
Answer
The loudness and pitch of a sound note depends on intensity and frequency.
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Question 111 Mark
Mode of wave propagation in which particles of medium vibrate perpendicular to direction of propagation is known as _______.
Answer
Mode of wave propagation in which particles of medium vibrate perpendicular to direction of propagation is known as transverse wave.
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Question 121 Mark
_______ is mode of transfer of energy and momentum in the form of vibrations of particles of medium.
Answer
Mechanical wave is mode of transfer of energy and momentum in the form of vibrations of particles of medium.
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Question 131 Mark
Two sound waves of slightly different frequency moving in the same direction give rise to _______.
Answer
Two sound waves of slightly different frequency moving in the same direction give rise to beats.
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Question 141 Mark
_______ waves do not transfer any energy and momentum in the material medium.
Answer
Standing waves do not transfer any energy and momentum in the material medium.
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Question 151 Mark
The quantity which does not change when sound enters from one medium to another is ________.
Answer
The quantity which does not change when sound enters from one medium to another is frequency.
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Question 161 Mark
The apparent frequency in Doppler's effect does not depend upon _______.
Answer
The apparent frequency in Doppler's effect does not depend upon distance between observer and source.
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