Light — Key Formulas
- Mirror formula: 1/v + 1/u = 1/f
- Magnification (mirror): m = −v/u = h′/h
- Focal length of a spherical mirror: f = R/2
- Lens formula: 1/v − 1/u = 1/f
- Magnification (lens): m = v/u = h′/h
- Power of a lens: P = 1/f (f in metres), unit dioptre (D)
- Refractive index: n = c/v = sin i / sin r
- Laws of reflection: ∠i = ∠r