Concepts Of Physics MCQ Edition [Volume 1]PhysicsSound Waves
Two sound waves travel in the same medium along the same direction. The waves possess identical pressure amplitudes, but the first wave's wavelength is twice that of the second. If P₁ and P₂ denote the average power transmitted across a cross section by the first and second waves respectively, then
Options
- AP₂ = 2 P₁
- BP₁ = 4 P₂
- CP₂ = 4 P₁
- DP₁ = P₂
Correct answer
D. P₁ = P₂
Step-by-step solution
The average power transmitted across a cross-section of area A by a sound wave is given by P = I A , where I is the intensity of the wave. The intensity of a sound wave in terms of its pressure amplitude P₀ is given by I = ( P₀)^2 2 v , where is the density of the medium and v is the speed of sound in the medium. Since both waves travel in the same medium, and v are the same for both waves. It is given that both waves have identical pressure amplitudes, so P₀ is also the same. Therefore, the intensity I is independ