Curious

             Polarisation The phenomenon of restricting the waves in oscillation to particular plane is called polarisation.                             Note A wave having oscillation in all possible direction is said to be polarised.  When the all oscillation get can fined along one direction the wave is called plane polarised.  Representation of Unpolarised and polarised Pictorial representations of Unpolarised light Plane polarised light: (a) vibrations parallel to the plane of paper. (b) vibrations perpendicular to the plane of paper.  Experimental demonstration of polarisation Intensity depends upon the angle between polariser axis and analyser axis.  Law of molus It States that the intensity of polarised light transmitted through the analyser varies as the square of cosine of the angle between the plane of transmission of analyser and polariser.  ...

   Huygens principal According to this principal the particles on wave front behaves like fresh source of light emit waves in all direction called secondary wavelets and the envelop (tangential surface) in the forward direction to the secondary wavelets gives the new position of wavefront in the medium.     Construction The light ray passes normally through the wave front and the disturbance propagates with the direction of speed of light in the medium If disturbance taken 't' time to reach from AB to PQ It covers,                    d = c × t       Where, d = distance from AB to PQ Now on drawing sphere of radius ct around particle in PQ  Then the tangential surface on sphere in forward direction gives a new position A forward wave front.  Laws of reflection from Huygen's principal If wavefront taken 't' time from B to C with 'v' velocity        BC = vt Taken and arc ...