Question

In both the laws of reflection and the laws of refraction, the angles of incidence, reflection, and refraction are measured with respect to:

Options

• The refracted ray

• The surface of the medium

• The normal at the point of incidence

• The tangent at the point of incidence

Answer 1

In both reflection and refraction, all angles are defined between the ray and the normal drawn at the point of incidence — never with the surface itself. This convention keeps Snell's law \[n_1 \sin\theta_1 = n_2 \sin\theta_2\] consistent.