Question

Amplitudes of two light waves of the same frequency are in the ratio $4:3$. What will be the ratio of maximum and minimum intensities if the two wave interfere?

Answer 1

when waves interfere, the value at any particular position and instant is the sum of the values of the waves.

$\therefore$ The maximum amplitude of interference is the sum of the amplitudes and minimum is the absolute value of their difference.

If the amplitudes are $4x$ and $3x$, then the maximum amplitude of thier interference is $7x$ and minimum is $1x$.

making the interference amplitudes $7:1$

intensity is proportional to the square of the amplitude.

making the ratio of the intensities $49:1$.