Question

If the ratio of maximum and minimum intensities of an interference pattern is $36:1$, then the ratio of amplitudes of the two interfering waves will be

• A. $7:5$
• B. $3:7$
• C. $7:4$
• D. $3:4$

Answer 1

The correct option is A $7:5$

Let $a_1,a_2$ be amplitudes of waves

ratio of maximum to minimum intensity is given by

$\frac{I_{max}}{I_{min}}=\frac{(a_1+a_2{)}^2}{(a_1-a_2{)}^2}\frac{a_1+a_2}{a_1-a_2}=\sqrt{\frac{36}{1}}=6\frac{a_1}{a_2}=\frac{7}{5}$