Wavefront: Suggested by Huygens.The locus of all particles in a medium,vibrating in the same phase is called wave front (Wf).
The direction of propagation of light (ray of light) is.perpendicular to Wf. Every point on the given wave front acts as a source of new disturbance called secondary wavelengths which travel in all direction with the velocity of light in the medium. A surface touching these secondary wavelengths langentially in the forward direction at any instant gives the new wavefront at that instant. This is called secondary wavefront. Application of Huygen's principle to study refraction and reflection.
Reflection.RC = AD
∠i = ∠r
Which proves law of reflection.
Reflection:
Which proves law of refraction.
