In case of interference of two waves each of intensity I0, the intensity at a point of constructive interference will be

Question

In case of interference of two waves each of intensity I0, the intensity at a point of constructive interference will be (A) 4 I0 for coherent source (B) 2 I0 for coherent source (C) 4 I0 for incoherent source (D) 2 I0 for incoherent source

Tardigrade Admin · Accepted Answer

When the sources are coherent, R2=a2+b2+2 a b cos φ for constructive interference, φ = 0 ∴ I=I0+I0+2 √I0 I0 cos 0°=4 I0 When the sources are incoherent, intensities just add I=I0+I0=2 I0

Q. In case of interference of two waves each of intensity $I_{0}$ , the intensity at a point of constructive interference will be

$4 I_{0}$ for coherent source

$2 I_{0}$ for coherent source

$4 I_{0}$ for incoherent source

$2 I_{0}$ for incoherent source

When the sources are coherent,
$R^{2} = a^{2} + b^{2} + 2 ab cos ϕ$
for constructive interference, $ϕ = 0$
$∴ I = I_{0} + I_{0} + 2 I_{0} I_{0} cos 0^{\circ} = 4 I_{0}$
When the sources are incoherent, intensities just add
$I = I_{0} + I_{0} = 2 I_{0}$

Q. In case of interference of two waves each of intensity I0​, the intensity at a point of constructive interference will be

4I0​ for coherent source

2I0​ for coherent source

4I0​ for incoherent source

2I0​ for incoherent source