Snell's law

Snell's law is a formula used for calculating the angle of incidence and the angle of refraction when light passes from one material into another. If light is travelling from medium 1 to 2, t states that 
:\frac{\sin \theta_1}{\sin \theta_2} = \frac{n_1}{n_2} = \frac{v_1}{v_2}
where θ is the angle of incidence/refraction, n is the refractive index, and v is the velocity of light.
Category:Optics