Ray Optics Formula Sheet — Class 12 Physics

Concept	Formula	Symbols Defined
Mirror Equation	\[\frac{1}{v} + \frac{1}{u} = \frac{1}{f}\]	v = image distance, u = object distance, f = focal length
Focal Length (Mirror)	\[f = \frac{R}{2}\]	R = radius of curvature
Lateral Magnification	\[m = \frac{h'}{h} = -\frac{v}{u}\]	h' = image height, h = object height
Snell's Law	\[n_1 \sin i = n_2 \sin r\]	n = refractive index, i = angle of incidence, r = angle of refraction
Refractive Index	\[n = \frac{c}{v}\]	c = speed of light in vacuum, v = speed in medium
Optical Path	\[d' = nd\]	d' = optical path, n = refractive index, d = actual distance
Critical Angle	\[\sin i_c = \frac{n_2}{n_1}\]	ic = critical angle, n1 = denser medium, n2 = rarer medium
Lens Maker's Formula	\[\frac{1}{f} = (n-1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)\]	f = focal length, n = refractive index, R1, R2 = radii of curvature
Lens Equation	\[\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\]	v = image distance, u = object distance, f = focal length
Power of a Lens	\[P = \frac{1}{f}\]	P = power (in Diopters if f is in meters)
Prism Refractive Index	\[n = \frac{\sin(\frac{A+D}{2})}{\sin(\frac{A}{2})}\]	A = angle of prism, D = angle of minimum deviation
Dispersive Power	\[\omega = \frac{n_V - n_R}{n - 1}\]	nV, nR = indices for violet and red, n = mean refractive index
Rayleigh Scattering	\[I \propto \frac{1}{\lambda^4}\]	I = intensity of scattered light, \lambda = wavelength

Ray Optics - Formula Sheet