Question

The intensity ratio of two coherent sources of light is $p$. They are interfering in some region and produce interference pattern. Then the fringe visibility is

• A. $\frac{1+p}{2 \sqrt{p}}$
• B. $\frac{2 \sqrt{p}}{1+p}$
• C. $\frac{p}{1+p}$
• D. $\frac{2 p}{1+p}$

Answer 1

Answer: (B)

Visibility $V=\frac{I_{\max }-I_{\min }}{I_{\max }+I_{\min }}=\frac{2 \sqrt{I_{1} I_{2}}}{\left(I_{1}+I_{2}\right)}$
$=\frac{2 \sqrt{I_{1} / I_{2}}}{\left(\frac{I_{1}}{I_{2}}+1\right)}=\frac{2 \sqrt{P}}{(P+1)}$