Optics Question 855
Question: Two monochromatic light beams of intensity 16 and 9 units are interfering. The ratio of intensities of bright and dark parts of the resultant pattern is:
Options:
A) $ \frac{16}{9} $
B) $ \frac{7}{1} $
C) $ \frac{7}{1} $
D) $ \frac{49}{1} $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] $ Intensity\propto ~( amplitude ) $
$ \frac{I _{1}}{I _{2}}=\frac{16}{9}=\frac{a _{1}^{2}}{a _{2}^{2}}\Rightarrow a _{1}=4 $ ; $ a _{2}=3 $
Therefore the ratio of intensities of bright and dark parts $ \frac{I _{Bright}}{I _{Dark}}=\frac{{{(a _{1}+a _{2})}^{2}}}{{{(a _{1}-a _{2})}^{2}}}=\frac{{{(4+3)}^{2}}}{{{(4-3)}^{2}}}=\frac{49}{1} $
