Light: reflection

Mirror formula (image distance)1/v + 1/u = 1/f for spherical mirrors. With the sign convention, u is negative; f is negative for a concave mirror and positive for a convex mirror.

Light: refraction

Lens formula (image distance)1/v − 1/u = 1/f for thin lenses. u is negative; f is positive for a convex lens and negative for a concave lens.
Power of a lens (dioptre)P = 1/f with f in metres (P = 100/f with f in cm). Unit: dioptre (D). Convex lens: positive power; concave lens: negative. Powers of lenses in contact add.
Refractive index and speed of lightAbsolute refractive index n = c/v, with c = 3 × 10⁸ m/s. Relative index of medium 2 w.r.t. medium 1: n₂₁ = n₂/n₁ = v₁/v₂.

Magnification and nature of imageMirror: m = −v/u. Lens: m = v/u. m = h′/h. Negative m → real and inverted; positive m → virtual and erect; |m| > 1 → enlarged.

Magnetic effects: Fleming's rules and directionsRight-hand thumb rule: field around a wire. Fleming's left-hand rule (motor): forefinger = field, middle finger = current, thumb = force. Fleming's right-hand rule (generator): forefinger = field, thumb = motion, middle finger = induced current.

Acids, bases and the pH scalepH < 7 acidic, pH = 7 neutral, pH > 7 basic. Lower pH = more H⁺ ions; each step of 1 in pH is a 10-fold change in H⁺ concentration.

Periodic table: configuration, valency and trendsShells fill 2, 8, 8 for the first 20 elements. Valency = valence electrons (if ≤ 4) or 8 − valence electrons. Across a period (left → right) atomic size and metallic character decrease; down a group both increase.

Heredity: Mendel's ratios and probabilityMonohybrid cross (Tt × Tt): phenotype 3 : 1, genotype 1 TT : 2 Tt : 1 tt. Dihybrid cross (RrYy × RrYy): 9 : 3 : 3 : 1. Test cross (Tt × tt): 1 : 1.

Life processes, control and coordinationNutrition, respiration, transport and excretion keep organisms alive; nerves and hormones (in animals) and plant hormones (in plants) coordinate responses.