Q 12-10-029JEE MainJEE Main 2026 (6 Apr, Shift 1)Easy
In interference experiment the path difference between two interfering waves at a point $A$ on the screen is $\lambda/3$, where $\lambda$ is the wavelength of these waves, and at another point $B$ the path difference is $\lambda/6$. The ratio of intensities at points $A$ and $B$ is ______.
Answer: (C) $1/3$
Concept. $I\propto\cos^2\left(\dfrac{\pi\Delta x}{\lambda}\right)$.
Step 1. Point A. $\cos^2\dfrac\pi3=\dfrac14$.
Step 2. Point B. $\cos^2\dfrac\pi6=\dfrac34$.
Step 3. Ratio. $\dfrac{1/4}{3/4}=\dfrac13$.
Answer. Option C.
Solution by Sreeraj P, M.Sc Physics
