Optics Question 143
Question: In the Young’s double slit experiment, if the phase difference between the two waves interfering at a point is f, the intensity at that point can be expressed by the expression
[MP PET 1998; MP PMT 2003]
Options:
A) $ I=\sqrt{A^{2}+B^{2}{{\cos }^{2}}\varphi } $
B) $ I=\frac{A}{B}\cos \varphi $
C) $ I=A+B\cos \frac{\varphi }{2} $
D) $ I=A+B\cos \varphi $ Where A and B depend upon the amplitudes of the two waves.
Show Answer
Answer:
Correct Answer: D
Solution:
$ I=a _{1}^{2}+a _{2}^{2}+2a _{1}a _{2}\cos \varphi $
Put $ a _{1}^{2}+a _{2}^{2}=A $
and $ a _{1}a _{2}=B;\ \ \therefore I=A+B\cos \varphi $
