Question

In Young’s double slit experiment, the ratio of maximum to minimum intensities of the fringe system is$4:1$. The amplitudes of the coherent sources are in the ratio:

• A. $4:1$
• B. $3:1$
• C. $2:1$
• D. $1:1$

Answer 1

The correct option is B

$3:1$

Solution:

Step 1: Given information

The ratio of maximum to minimum intensities of the fringe system is$4:1$.

Step 2: Calculate the amplitudes of the coherent sources are in the ratio

Let the amplitude ratio be$\frac{x}{y}$.

The ratio of maximum and minimum is${\left[\frac{(x+y)}{(x-y)}\right]}^2$ which is equal to $\frac{4}{1}$.

Assume that $x>y$ so $\frac{(x+y)}{(x-y)}=\frac{2}{1}$

$x+y=2x–2y$

$\frac{x}{y}=\frac{3}{1}$

Hence, the correct option is (B).