A plate of thickness t made of a material of refractive index `mu` is placed in front of one of the slits in a double slit experiment. (a) Find the changes in he optical path due to introduction of the plate. (b) Wht should be the minimum thickness t which will make the intensity at the centre of the fringe pattern zero ? Wavelength of the light used is `lamda`. Neglect any absorption of light in the plate.
A. `(mu-1)(lambda)/(2)`
B. `(mu-1)lambda`
C. `(lambda)/(2(mu-1))`
D. `(lambda)/((mu-1))`
