An electromagnetic wave of wavelength is incident normally on a dielectric slab of thickness t. if k is the dielectric constant of the slab, the change in phase

An electromagnetic wave of wavelength IS incident normally on a dielectric slab of thickness t. If K is the dielectric constant of the slab, the change in phase of the emergent wave compared with the case of propagation in the absence of the dielectric slab is 5 2Tt (c) R-1) (a) VK-1 (b) 27T (d)