Question

Two sources of same intensity interfere at a point constructively to produce an intensity I. When one source is removed, what will be the intensity at that point?

Answer 1

We know that, $Intensity\alpha (Amplitude{)}^2$
Both sources have same intensity $\Rightarrow$ They have same amplitude (lets say A).
Initially, amplitude = A+A = 2A
$\therefore I=4A^2$
When one source removed, amplitude = A
$\therefore I^{\prime }=\frac{I}{4}$