OCR A-Level Physics/Equation Sheet

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

AS Formulae[edit]

Unit 1 - Mechanics[edit]

 \text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}} \times 100%

Kinematics Equations[edit]

  • 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[edit]

  •  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[edit]

  •  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[edit]

  •  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}}

Unit 2 - Electrons, Waves and Photons[edit]

Electricity[edit]

  • \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[edit]

  •  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}
  • The following equations are NOT given in the formulae booklet
    •  \text{intensity} = \frac{\text{power}}{\text{cross-section area}}
    • \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}

A2 Formulae[edit]

Unit 4 - The Newtonian World[edit]

Unit 5 - Fields, Particles and Frontiers of Physics[edit]