NEETPhysicsWave Optics
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In Young's double slit experiment, the ratio of intensity at a point where path difference is 4 to the intensity at the central maximum is 1:2 . Reason (R): The phase difference corresponding to a path difference of 4 is 2 , and intensity varies as the square of the cosine of half the phase differe
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
Step-by-step solution
Phase difference is related to path difference x by = 2 x . For x = 4 , = 2 4 = 2 . The intensity I at a point on the screen is given by I = I_ max ^2 ( 2 ) . Substituting = 2 , we get I = I_ max ^2 ( 4 ) = I_ max ( 1 2 )^2 = I_ max 2 . The ratio of intensity at this point to the central maximum intensity is 1:2 . Thus, Assertion (A) is correct. Reason (R) correctly states the phase difference and the formula for intensity variation, which directly explains the calculation in the Assertion. Thus, Reason (R) is corr