Physics: Wave Optics MCQs

The pressure wave, P = 0.01 sin[1000t – 3x] Nm^–2, corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is 0°C. On some other day when temperature is T, the speed of sound produced by the same blade and at the same frequency is found to be 336 ms^–1. Approximate value of T is :

A small speaker delivers 2 W of audio output. At what distance from the speaker will one detect 120 dB intensity sound ? [Given reference intensity of sound as 10^–12 W/m² ]

A progressive wave traveling along the positive x-direction is represented by y(x,t) = Asin (kx – ωt + Φ). Its snapshot at t = 0 is given in the figure.

For this wave, the phase Φ is :

For a transverse wave travelling along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m) of the waves are :

Assume that the displacement (s) of air is proportional to the pressure difference (Dp) created by a sound wave. Displacement (s) further depends on the speed of sound (v), density of air (r) and the frequency ( f ). If Dp ~ 10Pa, v ~ 300 m/s, r ~ 1 kg/m³ and f ~ 1000 Hz, then s will be of the order of (take the multiplicative constant to be 1)