Question

Two coherent sources of intensity ratio 1 : 4 produce an interference pattern. The visibility of fringes will be

• A. $1$
• B. $0.6$
• C. $0.8$
• D. $0.4$

Answer 1

The correct option is C $0.8$

Given that the ratio of the intensities is:

$\frac{I_1}{I_2}=\frac{1}{4}$

$\Rightarrow I_1=k$ and $I_2=4k$

We know that finge visibility is given as:

Fringe visibility $V=\frac{2\sqrt{I_1{I}_2}}{(I_1+I_2)}$

$=\frac{2\sqrt{k\times 4k}}{(k+4k)}=0.88$