Q 12-10-041JEE MainJEE Main 2026 (24 Jan, Shift 2)Medium
In the Young's double slit experiment the intensity produced by each one of the individual slits is $I_o$. The distance between two slits is 2 mm . The distance of screen from slits is 10 m . The wavelength of light is $6000\ \text{Å}$. The intensity of light on the screen in front of one of the slits is ______
Answer: (B) $I_o$
The point in front of a slit is at $y = \dfrac d2 = 1$ mm from the centre.
Path difference:
$$\Delta = \frac{yd}{D} = \frac{10^{-3}\times2\times10^{-3}}{10} = 2\times10^{-7}\ \text{m}$$
Phase difference:
$$\phi = \frac{2\pi}{\lambda}\Delta = \frac{2\pi\times2\times10^{-7}}{6\times10^{-7}} = \frac{2\pi}{3}$$
$$I = 4I_o\cos^2\frac\phi2 = 4I_o\cos^2 60^\circ = 4I_o\times\frac14 = I_o$$
Solution by Sreeraj P, M.Sc Physics