Q. No.The speed of sound in air is:
1.
dependent on pressure.
2.
decreases with temperature.
3.
independent of temperature.
4.
increases with humidity.
A bat emits an ultrasonic sound of frequency 1000 kHz in the air. If the sound meets a water surface, what is the wavelength of the reflected sound? (The speed of sound in air is 340 m/sec and in water is 1486 m/sec)
1. \(3.4 \times 10^{-4}~\text{m}\)
2. \(1 . 49 \times 10^{- 3} ~ \text{m}\)
3. \(2 . 34 \times 10^{- 2} ~\text{m}\)
4. \(1 . 73 \times10^{- 3} ~\text{m}\)
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 \(340~\mathrm{m/s}\) and in water \(1486~\mathrm{m/s}\))
| 1. | \(3.4 \times 10^{-4} \mathrm{~m} \) | 2. | \(1.4 \times 10^{-3} \mathrm{~m} \) |
| 3. | \(2.5 \times 10^{-4} \mathrm{~m} \) | 4. | \(1.8 \times 10^{-3} \mathrm{~m}\) |
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. \(2.0 \times10^{-4}~\text{m}\)
A transverse harmonic wave on a string is described by, \(y(x,t) = 3.0 sin ( 36t + 0.018x + {\pi \over 4})\) where x and y are in cm and t in sec. The positive direction of x is from left to right. What is the shortest distance between two successive crests in the wave?
| 1. | 1.3 m | 2. | 3.0 m |
| 3. | 2.5 m | 4. | 3.5 m |
For the travelling harmonic wave, \(y(x,t) = 2.0\ cos\ 2\pi (10t - 0.0080x + 0.35 )\) where \(x\) and \(y\) are in \(\text{cm}\) and \(t\) is in seconds. The phase difference between the oscillatory motion of two points separated by a distance of \(4~\text{m}\) will be:
1. \(0.8 \pi\ \text{rad}\)
2. \(\pi\ \text{rad}\)
3. \(6.4\pi\ \text{rad}\)
4. \(4\pi\ \text{rad}\)
\(y(x,t)=0.06\sin\Big(\frac{2\pi}{3}x\Big)\cos(120\pi t)\)
where \(x\) and \(y\) are in metre and \(t\) in second. The length of the string is \(1.5\) m and its mass is \(3\times10^{-2}\) kg. The tension in the string is:
1. \(540\) N
2. \(648\) N
3. \(200\) N
4. \(425\) 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
A one-meter long tube open at one end, with a movable piston at the other end, shows resonance with a fixed frequency source (a tuning fork of frequency 340 Hz) when the minimum tube length is 25.5 cm. The speed of sound in air at the temperature of the experiment is: (The edge effects may be neglected.)
1. 324.16 m/s
2. 320 m/s
3. 345 m/s
4. 346.8 m/s
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