Ray Optics and Optical Instruments

The angle of incidence equals

The angle of incidence equals the angle of reflection, and the incident ray, reflected ray, and normal lie in the same plane. These laws apply to all

The ratio of sine of angle

The ratio of sine of angle of incidence to sine of angle of refraction is constant: sin i/sin r = n₂₁ (refractive index of medium 2 with respect to me

When light travels from denser

When light travels from denser to rarer medium at angles greater than the critical angle, it is completely reflected back. Critical angle: sin iₓ = n₂

1/v + 1/u = 1/f

1/v + 1/u = 1/f, where u is object distance, v is image distance, and f is focal length. For spherical mirrors, f = R/2.

1/v

1/v - 1/u = 1/f for thin lenses. Combined with lens maker's formula: 1/f = (n₂₁ - 1)(1/R₁ - 1/R₂).