Monochromatic light of wavelength 5000 Å is incident on two slits separated by a distance of 5 × 10^–4 m. Interference pattern is seen on the screen placed at a distance of 1 m from the slits. A thin glass plate of thickness 1.5 × 10^–6 m and refractive index 1.5 is placed between one of the slits and the screen. If intensity in the absence of plate was I_o then new intensity at the center of the screen will be

Zero

$\text{ After placing the glass sheet path difference is }\Delta x = (\mu -1)t $

$\text{Phase difference is } \phi = \frac{2\pi}{\lambda} \Delta x = \frac{2\pi}{\lambda} (\mu -1)t = \frac{2\pi}{5\times 10^{-7}} {0.5\times 1.5\times 10^{-6}} = 3\pi$

$ I_R = 0$