Q. No.A bat emits an ultrasonic sound of frequency \(1000~\text{kHz}\) in the air. If the sound meets a water surface, what is the wavelength of the refracted sound?
(speed of sound in air is \(340~\text{m/s}\) and in water \(1486~\text{m/s}\))
1.
\(3.4 \times 10^{-4}~\text {m} \)
2.
\(1.4 \times 10^{-3}~\text {m} \)
3.
\(2.5 \times 10^{-4}~\text {m} \)
4.
\(1.8 \times 10^{-3}~\text {m} \)
A hospital uses an ultrasonic scanner to locate tumors in a tissue. What is the wavelength of sound in the tissue in which the speed of sound is \(1.7~\text{km/s}\)? The operating frequency of the scanner is \(4.2~\text{MHz}\).
| 1. | \(3.0 \times10^{-4}~\text{m}\) | 2. | \(4.0 \times10^{-4}~\text{m}\) |
| 3. | \(3.5 \times10^{-4}~\text{m}\) | 4. | \(2.0 \times10^{-4}~\text{m}\) |
| 1. | \(1.3\) m | 2. | \(3.0\) m |
| 3. | \(2.5\) m | 4. | \(3.5\) m |
1. \(0.8 \pi~\text{rad}\)
2. \(\pi~ \text{rad}\)
3. \(6.4\pi~\text{rad}\)
4. \(4\pi~\text{rad}\)
\(y(x,t)=0.06\sin\Big(\dfrac{2\pi}{3}x\Big)\cos(120\pi t)\)
where \(x\) and \(y\) are in meter and \(t\) in second. The length of the string is \(1.5~\text{m}\) and its mass is \(3\times10^{-2}~\text{kg}.\) The tension in the string is:
1. \(540~\text{N}\)
2. \(648~\text{N}\)
3. \(200~\text{N}\)
4. \(425~\text{N}\)
| 1. | a stationary wave |
| 2. | a travelling wave |
| 3. | both stationary and travelling wave |
| 4. | none of the above |
A wire stretched between two rigid supports vibrates in its fundamental mode with a frequency of 45 Hz. The mass of the wire is kg and its linear mass density is kg/m. What is the speed of the transverse wave on the string?
1. 74.31 m/s
2. 75.70 m/s
3. 78.75 m/s
4. 72 m/s
(The edge effects may be neglected.)
1. \(324.16~\text{m/s}\)
2. \(320~\text{m/s}\)
3. \(345~\text{m/s}\)
4. \(346.8~\text{m/s}\)
A steel rod \(100~\text{cm}\) long is clamped at its middle. The fundamental frequency of the longitudinal vibrations of the rod is given to be \(2.53~\text{kHz}.\) What is the speed of sound in steel?
1. \(5.06~\text{km/s}\)
2. \(5.12~\text{km/s}\)
3. \(4.29~\text{km/s}\)
4. \(4.01~\text{km/s}\)
Two sitar strings, \(A\) and \(B,\) playing the note \(\mathrm{Ga},\) are slightly out of tune and produce \(6~\text{Hz}\) beats. The tension in the string \(A\) is slightly reduced, and the beat frequency is found to be reduced to \(3~\text{Hz}.\) If the original frequency of \(A\) is \(324~\text{Hz},\) what is the frequency of \(B?\)
1. \(316~\text{Hz}\)
2. \(318~\text{Hz}\)
3. \(319~\text{Hz}\)
4. \(314~\text{Hz}\)
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