Formulate the law of light reflection and deduce it using Huygens’ principle.

The angle of incidence is equal to the angle of reflection. The incident beam, the reflected beam and the perpendicular reconstructed at the point of incidence to the reflecting surface lie in the same plane.
The wave incident at an angle reaches points A and B ‘of the interface at different times. At the moment when the wave front reaches point A, this point becomes a source of secondary waves. As the wave hits points 1, 2,3, B ‘, they all become sources of secondary waves. The front of the reflected wave is a flat surface tangent to the spherical fronts of the secondary waves.