VCE Physics cheat sheet

Specific heat capacity: Q = mcΔT, where c is energy per kilogram per kelvin; latent heat: Q = mL for a phase change at constant temperature.

Thermal equilibrium occurs when two objects in contact reach the same temperature; net heat transfer is then zero, and heat flows from hot to cold.

Newton's law of cooling: rate of heat loss is proportional to temperature difference from surroundings, so cooling curves are exponential.

Snell's law: n1 sin θ1 = n2 sin θ2; refractive index n = c/v, so light slows in a denser medium and bends toward the normal.

Total internal reflection occurs only when light travels from higher to lower n and the angle of incidence exceeds the critical angle, sin θc = n2/n1.

Wave equation: v = fλ; frequency is set by the source and is unchanged on refraction, while speed and wavelength change.

For a string fixed at both ends, resonant wavelengths are λ = 2L/n, giving harmonics f_n = nv/(2L).

Radiation intensity follows the inverse-square law: I ∝ 1/r², so doubling distance quarters the intensity.

Superposition: displacements add algebraically; constructive interference needs path difference mλ, destructive needs (m + ½)λ.

Constant-acceleration equations: v = u + at, s = ut + ½at², v² = u² + 2as; these apply only when acceleration is constant.

Newton's second law: net force F = ma; weight W = mg and normal force are separate forces, not a Newton's-third-law pair.

Momentum p = mv is conserved in collisions with no external net force; kinetic energy is conserved only in elastic collisions.

Work W = Fs cos θ and power P = W/t = Fv; energy is conserved, with work done against friction becoming heat.

Circular motion: centripetal acceleration a = v²/r directed toward the centre; the net force must point inward.

Ohm's law V = IR; resistors in series add, while in parallel 1/R_total = Σ1/R.

Electrical power: P = VI = I²R = V²/R; energy consumed is E = Pt, billed in kilowatt-hours.

Magnetic force on a current-carrying wire: F = BIL sin θ, direction given by the right-hand rule; parallel currents attract.

Electromagnetic induction: a changing magnetic flux induces an emf; Faraday's law ε = −N ΔΦ/Δt, with Lenz's law opposing the change.

Projectile motion: horizontal velocity is constant; vertical motion has a = g downward, so the two components are analysed independently.

In uniform circular motion, speed is constant but velocity changes direction, so acceleration is nonzero and points to the centre.

Gravitational field strength g = GM/r²; gravitational potential energy near Earth U = mgh, and generally U = −GMm/r.

Kepler's third law: T² ∝ r³, so orbital period squared is proportional to orbital radius cubed for a given central mass.

For a satellite in circular orbit, gravitational force supplies the centripetal force: GMm/r² = mv²/r, giving v = √(GM/r).

Magnetic flux Φ = BA cos θ; induced emf equals the negative rate of change of flux linkage, ε = −N ΔΦ/Δt.

Transformers: V_s/V_p = N_s/N_p; an ideal transformer conserves power, so V_p I_p = V_s I_s.

Electric field between parallel plates is uniform: E = V/d, and the force on a charge is F = qE.

Charged particles in magnetic fields move in circles: qvB = mv²/r, giving r = mv/(qB).

Photoelectric effect: photons of energy E = hf; emission occurs only if hf exceeds the work function W, with maximum kinetic energy hf − W.

Stopping voltage V_s satisfies eV_s = hf − W, so a graph of V_s against f has slope h/e and intercept −W/e.

Threshold frequency f_0 = W/h; below this frequency no emission occurs regardless of intensity, because intensity only changes photon number.

de Broglie wavelength: λ = h/p = h/(mv), so faster or heavier particles have shorter wavelengths.

Bohr model: electron energy levels are discrete; a photon is emitted when an electron falls between levels, with energy equal to the difference.

Line spectra arise because photon energies are fixed by level differences; absorption lines occur at the same wavelengths as emission lines.

Double-slit interference: fringe spacing Δx = λL/d for small angles, where d is slit separation and L is slit-to-screen distance.

Diffraction is greatest when the wavelength is comparable to the gap size; a wider single slit gives a narrower central maximum.

Matter waves confirm wave-particle duality: electrons produce interference patterns, yet individual electrons arrive as discrete detections.