Physics Formulae
Values are given to three significant figures, except where more are useful.
speed of light in a vacuum  c  3.00 × 10^{8} m s^{–1} 
permittivity of free space  ε0  8.85 × 10^{–12} C^{2} N^{–1} m^{–2} (F m^{–1}) 
elementary charge  e  1.60 × 10^{–19} C 
Planck constant  h  6.63 × 10^{–34} J s 
gravitational constant  G  6.67 × 10^{–11}N m^{2 }kg^{–2} 
Avogadro constant  N_{A}  6.02 × 10^{23} mol^{1 } 
molar gas constant  R  8.31 J mol^{1 }K^{–1} 
Boltzmann constant  k  1.38 × 10^{23} J K^{–1} 
electron rest mass  m_{e}  9.11 × 10^{31} kg^{} 
proton rest mass  m_{p}  1.673 × 10^{27} kg^{} 
neutron rest mass  m_{n}  1.675 × 10^{27} kg^{} 
alpha particle rest mass  m_{a}  1.646 × 10^{27} kg^{} 
acceleration of free fall  g  9.81 m s^{–2} 
Formula 
Name 
Comments 
Wave Equation 
v= velocity (m/s) 

Intensity Law 
I = intensity (no units) 

Snell’s Law 
v1 = speed in first medium


Electric Field 
E = Electric field (N/C, V/m) 

Ohm’s Law 
R = resistance (W) 

Energy = VIt 
Electrical Energy 
Energy (J) 
P=VI 
Electrical Power 
P = power (W) 
Average Velocity 
vav = average velocity (m/s) 

Average Acceleration 
= average acceleration (ms2) 

Newton’s Second Law 
= sum of all forces (N) 

Kinetic Energy 
Ek = kinetic energy (J) 

Momentum 
P = momentum (Ns, kgm/s) 

Impulse 
Impulse = change in momentum (Ns, kgm/s) 

Universal Gravitation 
F = force (N) 

Kepler’s Third Law 
r = radius of motion (m) 

Gravitational Potential Energy 
Ep = Potential energy 

Gravitational Force 
F = force (N) 

Newtons’ Laws of Motion 
ux = initial speed in x direction (m/s) 

Kepler’s third law  r = radius of motion (m) 

Relativistic Length Contraction  Lv = apparent length (m) 

Relativistic time dilation  tv = apparent time (s) 

Magnetic force on a currentcarrying wire of length l in a magnetic field  B= Magnetic Field (T) I = current (A) l = length (m) 

Force per unit length  F = force (N) l = length (m) per unit I1, I2 = two currents parallel=repulsive, antiparallel=attractive d = separation of the two currents (m) k=magnetic constant (2 X 107 NC1m1) 

torque  t =torque (Nm) F =force (N) d=distance (m) 

torque on a coil immersed in a magnetic field 
t =torque (Nm) 

Transformer equation  Vp = primary voltage (V) 

Magnetic force on a charge in a magnetic field  F = force (N) 

Electric Field  E = Electric Field (N/C, V/m) 

Energy of a Photon  E = Energy (J) 

Wave Equation 
c = speed of light 3 X 108 m/s 