xP−xQ=(d+2.5)−(d−2.5)=5m Phase difference Δϕ due to path difference =
2π
λ
(Δx)=
2π
20
(5)=
π
2
At A,Q is ahead of P by path, as wave emitted by Q reaches before wave emitted by P. ∴ Total phase difference at A
π
2
−
π
2
=0 (due to P being ahead of Q by 90° ) IA=I1+I2+2√I1√I2cosΔϕ =I+I+2√I√Icos(0)=4I For C Path difference, xQ−xP=5m Phase difference Δϕ due to path difference =