A man sitting on a moving train hears the whistle of the engine. If the frequency of the whistle is 600 Hz, then:

1. the apparent frequency as heard by him is smaller than 600 Hz.

2. the apparent frequency is larger than 600 Hz.

3. the frequency as heard by him is 600 Hz.

4. None of the above

A policeman buzzes a whistle of frequency 420 Hz. A car with an audio recorder is moving towards the policeman with a speed of 72 km/h, recording a frequency of ${\mathrm{v}}_1$. If, after crossing, it records the frequency of ${\mathrm{v}}_2$, then ${\mathrm{v}}_1$- ${\mathrm{v}}_2$  is: (Velocity of sound is 300 m/s)

1. $\sqrt{2}$ Hz

2. 20 Hz

3. 28 Hz

4. 56 Hz

Two progressive waves are represented by, \(y_1=5sin(200t-3.14x)\) and
 \(y_2=10sin(200t-3.14x+\frac{\pi}{3})\) (\(x\) is in metres, and \(t\) is in seconds). Path difference between the two waves is:
1. $\frac{100}{\mathrm{\pi }}\mathrm{ m}$

2. $\frac{1}{3}\mathrm{ m}$

3. $3.14\times \frac{\mathrm{\pi }}{3}\mathrm{ m}$

4. $\frac{{\mathrm{\pi }}^2}{9}\mathrm{ m}$

Two organ pipes closed at one end produce \(5\) beats per second in fundamental mode. If the ratio of their lengths is \(10:11\), then their frequencies (in Hz) are:

If a travelling wave pulse is given by \(y=\frac{20}{4+(x+4 t)^2}~\text{m}\), then:

Two wires, A and B, of a musical instrument 'Sitar' produce 3 beats per second. If the tension of B is raised, the number of beats becomes 1 beat per second. If the frequency of A is 450 Hz, then the original frequency of B will be:

1. 447 Hz

2. 453 Hz

3. 449 Hz

4. 451 Hz

A train moves towards a stationary observer at 50 m/s. The train sounds a whistle and its frequency is registered by the observer as ${\mathrm{f}}_1$. If the train's speed is increased by 25 m/s, the frequency registered is ${\mathrm{f}}_2$. If the speed of sound is 300 m/s, then ${\mathrm{f}}_1$:${\mathrm{f}}_2$ is:

1. 3:5

2. 5:7

3. 7:9

4. 9:10

A cylindrical tube open at both ends has a fundamental frequency f₀ in the air. The tube is dipped vertically in water such that half its length is inside water. The fundamental frequency of the air column now will be:

1. $\frac{3f_{\mathit{0}}}{4}$

2. $f_0$

3. $\frac{f_{\mathit{0}}}{2}$

4. 2$f_0$

The maximum possible wavelength in an open organ pipe of length l is:

The equation of a stationary wave is given as $\mathrm{y}=\mathrm{A}$ $\sin$ $0.5\mathrm{\pi t}$ $\cos (0.2\mathrm{\pi x}),$ $$ where t is in seconds and x in centimetres. Which of the following is correct?