Three equal-intensity sources S₁, S₂ and S₃ lie on a straight line with S₁S₂ = S₂S₃. At a distant point P, the wave from S₂ is 120° ahead of S₁ and the wave from S₃ is 120° ahead of S₂. Find the resultant intensity at P.

Question

G1 Physics · Accepted Answer

Step 1: Add the waves as phasors. For two amplitudes A₁,A₂ with phase difference φ, A² = A₁² + A₂² + 2A₁A₂ cosφ. Step 2: Intensity is proportional to A²; constructive/destructive conditions are Δ = nλ and Δ = (n+½)λ. Step 3: Apply the stated phases/path differences. Final: 0.