Two sources of sound S₁ and S₂ vibrate at same frequency and are in phase. The intensity of sound detected at a point P as shown in the figure is I₀. (a) If θ equals 45°, what will be the intensity of sound detected at this point if one of the sources is switched off? (b) What will be the answer of the previous part if θ = 60°? Choose the option containing the correct final result.

Question

G1 Physics · Accepted Answer

Step 1: With both coherent sources on, the intensity at P is I₀. For equal source amplitudes, resultant intensity is 4Iₛ cos²(Δφ/2), where Iₛ is the intensity due to either source alone. Step 2: From the geometry shown, both θ = 45° and θ = 60° give the source pair in phase at P for the stated condition, so I₀ = 4Iₛ. Step 3: Switching off one source leaves intensity Iₛ = I₀/4 in each case. Final: D.