Optics Question 52
Question: Assertion : The film which appears bright in reflected system will appear dark in the transmitted light and vice-versa. Reason : The conditions for film to appear bright or dark in reflected light are just reverse to those in the transmitted light.
Options:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.
Show Answer
Answer:
Correct Answer: A
Solution:
For reflected system of the film, the maxima or constructive interference is $ 2\mu t\cos r=\frac{(2n-1)\lambda }{2} $ while the maxima for transmitted system of film is given by equation $ 2\mu t\cos r=n\lambda $ where t is thickness of the film and r is angle of reflection.
From these two equations we can see that condition for maxima in reflected system and transmitted system are just opposite.
