Question

Assertion :In Young's experiment, for two coherent sources, the resultant intensity is given by $I=4I_0{\cos }^2\frac{\varphi }{2}$ Reason: Ratio of maximum to minimum intensity is $\frac{I_{max}}{I_{min}}=\frac{{(\sqrt{I_1}+\sqrt{I_2})}^2}{{(\sqrt{I_1}-\sqrt{I_2})}^2}$

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

The expression in the assertion is the intensity at a point on the screen where coherent sources have an intensity of $I_0$ each and are out of phase by $\varphi$.

The expression in the reason is the ratio of maximum intensity to the minimum intensity in the interference pattern on a screen obtained when two sources of intensity $I_1$ and $I_2$ are used.

Both are true, but reason given is not the actual reason for the assertion here.