1)I have a basic doubt on polarization. It is given in book that the plane of polarization is perpendicular to the plane of vibration. What was need for defining the plane of polarization to be perpendicular to the plane of vibration? When I searched the internet, I found a site which says that the plane of polarization is the plane in which the magnetic field vector is oscillating and plane of vibration is the plane in which the electric field vector oscillates. In an electromagnetic wave, the electric field vector is perpendicular to the magnetic field vector. So this sounds to be true, but I would like have the opinion of this forum. When I referred Griffith's book on Electromagnetism I came across the fact that the polarisation vector defines the plane of vibration. Doesn't this mean that the plane of vibration is parallel to the plane of polarization? It also says that an electromagnetic wave propagating across the z-direction with its electric field vector along the x-direction and magnetic field vector along the y direction is said to be polarized in the x-direction.(Because by convention we use the direction of Electric field vector to specify the polarization of an electromagnetic wave).