Q97 / 180 · AIIMS 2001 · Physics

Two coherent monochromatic light beams of amplitude 3 and 5 units are superposed. The maximum and minimum possible intensities in the resulting beams are in the ratio

  • A
    $4: 2$
  • Correct answer
    B
    $16: 1$
  • C
    $8: 2$
  • D
    $4: 2$.

Solution

It is given that the amplitudes $A_1$ and $A_2$ are in the ratio $\frac{A_1}{A_2}=\frac{3}{5}$ $\therefore$ After superposition the maximum and minimum intensities will be in the ratio $$ \frac{I_{\max }}{I_{\min }}=\frac{\left(A_1+A_2\right)^2}{\left(A_1-A_2\right)^2}=\frac{(3+5)^2}{(3-5)^2}=\frac{8^2}{(-2)^2}=\frac{64}{4}=\frac{16}{1} $$

Hence, the correct answer is option: 'B'.

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