Question

Interference fringes are obtained using two coherent sources whose intensities are in the ratio 4 : 1. Then the ratio of the intensities of the bright and dark bands is

• A. 25:09:00
• B. 4:01
• C. 5:01
• D. 9:01

Answer 1

The Correct Option is D

$\frac{I_{max}}{I_{min}}=\frac{(a_1 +a_2 )^2}{(a_1 -a_2)^2}$$Here \,\frac{a_1^2}{a_2^2}=\frac{4}{1}i.e., \frac{a_1}{a_2}=\frac{2}{1}i.e., a_2 =\frac{a_1}{2}\therefore\,\frac{I_{ax}}{I_{min}}=\left(\frac{3a_1}{2}\right)^2 \times \left(\frac{2}{a_1}\right)^2=\frac{9}{1}$