An electromagnetic wave falls normally on the boundary between two isotropic dielectrics with refractive indices n1 and n2. Making use of the continuity condition for the tangential components, E and H across the boundary, demonstrate that at the interface the electric field vector E
(a) Of the transmitted wave experiences no phase jump;
(b) Of the reflected wave is subjected to the phase jump equal to π if it is reflected from a medium of higher optical density.