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Q. No.A gas is taken in a closed transparent tube, some lycopodium powder is spread within the tube, and the tube is placed horizontally. When the mouth of the tube is vibrated with a tuning fork of frequency \(1~\text{kHz,}\) and the length of the tube is adjusted: the powder is observed to collect in a wave-like pattern with adjacent 'maxima' separated by \(20~\text{cm}.\) The speed of sound in the gas is:
1.
\(100~\text{m/s}\)
2.
\(200~\text{m/s}\)
3.
\(400~\text{m/s}\)
4.
\(800~\text{m/s}\)
Subtopic: Speed of Sound |
Level 3: 35%-60%
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A waveform propagating along the \(x\text-\)axis is given by;
\(y(x,t)=(2~\text{mm})\sin2\pi\bigg[\big(300~\text{s}^{-1}\big)t-{\large\frac{x}{1.5~\text m}}\bigg] \)
The maximum speed of a particle as the wave travels is:
1. \(450~\text{m/s}\)
2. \(0.6~\text{m/s}\)
3. \(1.2\pi~\text{m/s}\)
4. \(900\pi~\text{m/s}\)
\(y(x,t)=(2~\text{mm})\sin2\pi\bigg[\big(300~\text{s}^{-1}\big)t-{\large\frac{x}{1.5~\text m}}\bigg] \)
The maximum speed of a particle as the wave travels is:
1. \(450~\text{m/s}\)
2. \(0.6~\text{m/s}\)
3. \(1.2\pi~\text{m/s}\)
4. \(900\pi~\text{m/s}\)
Subtopic: Wave Motion |
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Level 3: 35%-60%
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If the ambient pressure of air increases by \(2\%,\) the speed of sound in air:
| 1. | increases by \(2\%\) |
| 2. | increases by \(1\%\) |
| 3. | remains unchanged |
| 4. | decreases by \(1\%\) |
Subtopic: Speed of Sound |
58%
Level 3: 35%-60%
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Two different sources of sound having slightly different periods of vibration: \(1~\text{ms}\) and \(1.01~\text{ms},\) are sounded together. The resulting beat frequency is nearly:
1. \(100~\text{Hz}\)
2. \(50~\text{Hz}\)
3. \(10~\text{Hz}\)
4. \(0.01~\text{Hz}\)
1. \(100~\text{Hz}\)
2. \(50~\text{Hz}\)
3. \(10~\text{Hz}\)
4. \(0.01~\text{Hz}\)
Subtopic: Beats |
Level 3: 35%-60%
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The speed of sound in air within a room:
| 1. | changes with pressure and temperature |
| 2. | changes with pressure only |
| 3. | changes with temperature only |
| 4. | is unaffected by changes in pressure and temperature |
Subtopic: Speed of Sound |
56%
Level 3: 35%-60%
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A wave pulse travels along a taut string towards a fixed end as shown in the adjacent figures:
The reflected pulse is correctly shown by:
The reflected pulse is correctly shown by:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Wave Motion |
Level 4: Below 35%
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A string \((AB)\) under tension has a fundamental frequency of \(120~\text{Hz}.\) The string is set into vibration and a point \(P\) is held down by a finger so that it becomes a node (i.e., \(P\) does not vibrate):\(\Large\frac{AP}{PB}=\frac12.\) The lowest frequency for which this happens is:
1. \(120~\text{Hz}\)
2. \(240~\text{Hz}\)
3. \(360~\text{Hz}\)
4. \(180~\text{Hz}\)
1. \(120~\text{Hz}\)
2. \(240~\text{Hz}\)
3. \(360~\text{Hz}\)
4. \(180~\text{Hz}\)
Subtopic: Travelling Wave on String |
Level 3: 35%-60%
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A stone is dropped from the top of a hillock and the sound of it striking the ground is heard \(4.25~\text s\) later. The speed of sound in air is \(320~\text {m/s}\) and the value of \(g\) is \(10~\text {m/s}^2.\)
The time, required by the stone to reach the bottom, is:
1. \(4~\text s\)
2. \(2.125~\text s\)
3. \(0.25~\text s\)
4. \(2~\text s\)
The time, required by the stone to reach the bottom, is:
1. \(4~\text s\)
2. \(2.125~\text s\)
3. \(0.25~\text s\)
4. \(2~\text s\)
Subtopic: Speed of Sound |
53%
Level 3: 35%-60%
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A taut string of length \(2\) m is fixed at both ends and plucked. The speed of waves on the string is \(3\times10^4\) m/s (see figure).
If the wavelength of the fundamental frequency is \(\lambda_1,\) and the wavelength of the second harmonic is \(\lambda_2,\) what is the ratio \(\dfrac{\lambda_1}{\lambda_2}?\)
| 1. | \(0.5\) | 2. | \(1\) |
| 3. | \(2\) | 4. | \(4\) |
Subtopic: Standing Waves |
55%
Level 3: 35%-60%
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The addition of two waves with slightly different frequencies results in the production of beats or a beat frequency. The result can be monitored using an oscilloscope. Consider the two figures shown below:
Keeping the lower frequency wave constant, we increase the frequency of the other wave. You would expect the display on the oscilloscope to go from:
Keeping the lower frequency wave constant, we increase the frequency of the other wave. You would expect the display on the oscilloscope to go from:
| 1. | Figure \(\mathrm I\) to Figure \(\mathrm{II}\). |
| 2. | Figure \(\mathrm{II}\) to Figure \(\mathrm{I}\). |
| 3. | There will not be a shift between Figure \(\mathrm{I}\) and Figure \(\mathrm{II}\), but the amplitude will increase. |
| 4. | There will not be a shift between Figure \(\mathrm{I}\) and Figure \(\mathrm{II}\), but the display will become brighter. |
Subtopic: Beats |
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Level 3: 35%-60%
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