Question

If the intensity ratio of two coherent sources used in Young's double slit experiment is $49:1$, then the ratio between the maximum and minimum intensities in the interference pattern is

• A. $1:9$
• B. $9:16$
• C. $25:16$
• D. $16:25$
• E. $16:9$

Answer 1

Answer: (E)

$16:9$

The intensity ratio of two coherent sources becomes

$I_1=49\times I_2$

$I_{max}=I_1+I_2+2\sqrt{I_1{I}_2}=64I_2$

$I_{min}=I_1+I_2-2\sqrt{I_1{I}_2}=36I_2$

$\frac{I_{max}}{I_{min}}=\frac{64}{36}=16:9$