Question

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. 4:02
• B. 16:01
• C. 8:02
• D. 18:02

Answer 1

Answer: (B)

16:01

Answer 2

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 $\frac{I_{max}}{I_{min}} = \frac{\left(A_{1}+A_{2}\right)^{2}}{\left(A_{1}-A_{2}\right)^{2}}$ $= \frac{\left(3+5\right)^{2}}{\left(3-5\right)^{2}}$ $= \frac{8^{2}}{\left(-2\right)^{2}} =\frac{64}{4} = \frac{16}{1}$