A stretched wire of length \(1~\text{m},\) under an initial tension, vibrates with a fundamental frequency of \(256~\text{Hz}.\) When the tension in the wire is increased by \(1~\text{kg-wt},\) the fundamental frequency becomes \(320~\text{Hz}.\) What is the initial tension in the wire?

1. \(\dfrac{3}{4}~\text{kg-wt}\) 2. \(\dfrac{4}{3}~\text{kg-wt}\)
3. \(\dfrac{16}{9}~\text{kg-wt}\) 4. \(\dfrac{20}{9}~\text{kg-wt}\)

Subtopic:  Travelling Wave on String |
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The vibrations of four air columns under identical conditions are shown in the figure below. The ratio of their frequencies \(n_p: n_q: n_r: n_s\) will be: 
1. \(12:6:3:4\) 2. \(1:2:4:3\)
3. \(4:2:3:1\) 4. \(6:2:3:4\)
Subtopic:  Standing Waves |
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Which of the following expressions represents a wave?
1. \(y=A \sin (\omega t-kx)\)
2. \(y=A \cos ^2(a t-bx+c)+A \sin ^2(at-bx+c)\)
3. \(y=A \sin kx\)
4. \(y=A \sin \omega t\)
Subtopic:  Types of Waves |
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The fundamental frequency of vibration of a wire fixed at both ends is \(120~\text{Hz}.\) The wire can also vibrate in harmonics. The possible frequencies are:
1. \(60~\text{Hz},40~\text{Hz},30~\text{Hz},...\)
2. \(240~\text{Hz},360~\text{Hz},480~\text{Hz},...\)
3. \(240~\text{Hz},300~\text{Hz},360~\text{Hz},...\)
4. \(180~\text{Hz},240~\text{Hz},300~\text{Hz},...\)
Subtopic:  Beats |
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When a travelling wave is reflected off a fixed end, the reflected wave has:
1. the same frequency
2. a lower frequency
3. a higher frequency
4. a higher or a lower frequency
Subtopic:  Wave Motion |
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A string, under tension, and lying along the \(x\)-axis is set into transverse vibrations. The displacement at a point \(x\) is given by the function \(y(x,t)\) where \(t\) represents the time:    \(y(x,t)=\left ( 3~\text{mm} \right )\mathrm{sin}\left ( \frac{\pi x}{20~\text{cm}} \right ) \)\(\mathrm{cos}\left\{2\pi\left ( 100~\text{s}^{-1} \right )t \right\}\)
The maximum amplitude of vibration at any point on the string is:
1. \(3~\text{mm}\)
2. \(20~\text{cm}\)
3. \(300~\text{mm}\)
4. \(15~\text{mm}\)
Subtopic:  Standing Waves |
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A sinusoidal waveform whose displacement is given by:  
 \(y(x,t)=(5~\text{mm})\sin2\pi\)\(\large{\Big(\frac{x}{2~\text{m}}+\frac{t}{0.01~\text s}\Big)}\)

propagates along the \(x\)-axis. The wavelength of the waveform is:
1. \(\large\frac{2\pi}{2}\)\(~\text m\) 2. \(\large\frac{1}{2}\)\(~\text m\)
3. \(\large\frac{2}{2\pi}\)\(~\text m\) 4. \(2~\text m\)
Subtopic:  Wave Motion |
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A transverse wave is described by the equation:
        \(y=A \sin2 \pi\left(n t-x / \lambda_0\right) \)
If the maximum particle velocity is three times the wave velocity, then the wavelength \(\lambda_0=\)

1. \(\dfrac{\pi A}{3}\) 2. \(\dfrac{2 \pi A}{3}\)
3. \(\pi A\) 4. \(3 \pi A\)
Subtopic:  Wave Motion |
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A wave is described by the equation \( x=4 \cos \left(8 t-\dfrac{y}{2}\right) ,\) where \(x\) and \(y\) are in metres, and \(t\) is in seconds. The frequency of the wave (in \(\text{s}^{-1}\)) is:
1. \(\dfrac{4}{\pi}\) 2. \(\dfrac{8}{\pi}\)
3. \(\dfrac{2}{\pi}\) 4. \(\dfrac{\pi}{4}\)
Subtopic:  Wave Motion |
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If the fundamental frequency of the string is \(220~ \text{cps}\), the frequency of its fifth harmonic will be:
1. \(44~\text{cps}\) 2. \(55~\text{cps}\)
3. \(1100~\text{cps}\) 4. \(440~\text{cps}\)
Subtopic:  Travelling Wave on String |
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