OCR A-Level Physics/Equation Sheet

Equations, constants, and other useful data. Equations and constants are given in the formulae booklet unless stated otherwise.

Unit 1 - Mechanics
$$ \text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}} \times 100\% $$

Kinematics Equations

 * $$v = u + a t$$
 * $$a = \frac {\Delta v}{\Delta t} = \frac{v -u}{t}$$
 * $$ s = \frac{1}{2}(u + v)t $$
 * $$s = ut + \frac{1}{2}at^2$$
 * $$v^2 = u^2 + 2 a s $$

Forces, Moments and Pressure

 * $$ F_x = Fcos\theta$$
 * $$ F_y = Fsin\theta $$
 * $$F = ma $$
 * $$ W = mg $$
 * $$ \text{moment} = Fx $$
 * $$ \text{torque} = Fd $$
 * $$\rho = \frac{m}{V} $$
 * $$p = \frac{F}{A} $$

Work, Energy and Power

 * $$ W=F_xcos\theta$$
 * $$E_k = \frac{1}{2}mv^2 $$
 * $$E_p = mgh\ $$
 * $$P = \frac {\Delta W}{\Delta t} $$ Not given in formulae booklet.

Deforming Solids

 * $$ F = kx $$
 * $$ E = \frac{1}{2}Fx = \frac{1}{2}kx^2 $$
 * $$ \text{stress} = \frac{F}{A} $$
 * $$ \text{strain} = \frac{x}{L} $$
 * $$ \text{Young modulus} = \frac{\text{stress}}{\text{strain}} $$

Electricity

 * $$\Delta Q = I\Delta t $$
 * $$I = Anev $$
 * $$W=VQ $$
 * $$V=IR $$
 * $$R = \frac{\rho L}{A} $$
 * $$P = VI = I^2 R = \frac{V^2}{R} $$
 * $$W=VIt$$
 * $$e.m.f = V +Ir $$
 * $$V_\text{out} = \frac{R_2}{R_1 + R_2} \times V_\text{in} $$
 * $$R=R_1+R_2+\cdots $$
 * $$\frac{1}{R} = \frac{1}{R_1}+\frac{1}{R_2}+\cdots $$
 * If there are only two resistors, this simplified equation can be used which isn't given in booklet: $$R = \frac{R_1 R_2}{R_1+R_2}$$

Waves and Photons

 * $$ f = \frac{1}{T}$$ This is NOT given in the unit 2 section of the booklet but IS given in the unit 4 section.
 * $$v = f\lambda $$
 * $$\lambda = \frac{ax}{D} $$
 * $$E = hf = \frac{hc}{\lambda}$$
 * $$hf = \phi + KE_\text{max} $$
 * $$\lambda = \frac{h}{mv} $$
 * $$ \text{intensity} = \frac{\text{power}}{\text{cross-section area}}$$
 * The following equations are NOT given in the formulae booklet
 * $$\text{intensity}\propto\text{amplitude}^2$$
 * The following equation is known as Malus's Law:
 * $$I = I_0 cos^2{\theta}$$
 * Malus's Law can also be given in terms of amplitude:
 * $$ A = A_0 cos^2{\theta}$$