Optics Question 152
Question: In Young’s double slit experiment, the two slits act as coherent sources of equal amplitude A and wavelengthl. In another experiment with the same set up the two slits are of equal amplitude A and wavelength l but are incoherent. The ratio of the intensity of light at the mid-point of the screen in the first case to that in the second case is
[IIT-JEE 1986; RPMT 2002]
Options:
A) 1 : 2
B) 2 : 1
C) 4 : 1
D) 1 : 1
Show Answer
Answer:
Correct Answer: B
Solution:
Resultant intensity
At central position with coherent source (and
In case of incoherent at a given point, f varies randomly with time so (cos f)av = 0 \
Hence
