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 change in the optical path due to introduction of the plate. (b) What should be the maximum thickness t which will make the intensity at the centre of the fringe pattern zero ? Wavelength of the light used is `lambda`. Neglect any absorption of light in the plate.

Options

A. `(mu - 1)t, (lambda)/(2(mu-1))`
B. `2(mu - 1)t, (lambda)/(mu-1)`
C. `(mu - 1)t, (lambda)/(mu-1)`
D. `(mu - 1)(t)/(2), (lambda)/(mu-1)`

Answer

A