A person carrying a whistle emitting continuously a note of \(272~\text{Hz}\) is running towards a reflecting surface with a speed of \(18~\text{km/hr}\). The speed of sound in air is \(345~\text{m/s}\). The number of beats heard by him is: 
1. \(4\)
2. \(6\)
3. \(8\)
4. \(3\)

If the pressure amplitude in a sound wave is tripled, then the intensity of sound is increased by a factor of

(1) 9

(2) 3

(3) 6

(4) $\sqrt{3}$

If the amplitude of the sound is doubled and the frequency reduced to one-fourth, the intensity of sound at the same point will be :

(1) Increased by a factor of 2

(2) Decreased by a factor of 2

(3) Decreased by a factor of 4

(4) Unchanged

Intensity level of a sound of intensity I is 30 dB. The ratio $\frac{I}{I_0}$ is (Where I₀ is the threshold of hearing) 

(1) 3000

(2) 1000

(3) 300

(4) 30

Quality of a musical note depends on :

(1) Harmonics present

(2) The amplitude of the wave

(3) Fundamental frequency

(4) The velocity of sound in the medium

If T is the reverberation time of an auditorium of volume V then :

(1) $T\propto \frac{1}{V}$

(2) $T\propto \frac{1}{V^2}$

(3) $T\propto V^2$

(4) $T\propto V$

The intensity level due to two waves of the same frequency in a given medium are 1 bel and 5 bel. Then the ratio of amplitudes is :

(1) 1 : 4

(2) 1 : 2

(3) 1 : 10⁴

(4) 1 : 10²

Of the following the one which emits the sound of a higher pitch is :

(1) Mosquito

(2) Lion

(3) Man

(4) Woman

Two waves having sinusoidal waveforms have different wavelengths and different amplitudes. They will be having :

(1) Same pitch and different intensity

(2) Same quality and different intensity

(3) Different quality and different intensity

(4) Same quality and different pitch

The ends of a stretched wire of length L are fixed at x = 0 and x = L. In one experiment, the displacement of the wire is $y_1=A\sin (\pi x/L)\sin \omega t$ and energy is E₁, and in another experiment its displacement is $y_2=A\sin (2\pi x/L)\sin 2\omega t$ and energy is E₂. Then :

(1) E₂ = E₁

(2) E₂ = 2E₁

(3) E₂ = 4E₁

(4) E₂ = 16E₁