Physics can be broadly divided into Classical Physics, Quantum Physics, Modern Physics and Semiclassical Physics

Physics Formulae

Values are given to three significant figures, except where more are useful.

speed of light in a vacuum c 3.00 × 108 m s–1
permittivity of free space ε0 8.85 × 10–12 C2 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 × 10–11N m2 kg–2
Avogadro constant NA 6.02 × 1023 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 me 9.11 × 10-31 kg
proton rest mass mp 1.673 × 10-27 kg
neutron rest mass mn 1.675 × 10-27 kg
alpha particle rest mass ma 1.646 × 10-27 kg
acceleration of free fall g 9.81 m s–2

 

Formula

Name

Comments

*

Wave Equation

v= velocity  (m/s)
f = frequency (hz)
l = wavelength (m)

Intensity Law

I = intensity (no units)
d = distance (m)

Snell’s Law

v1 = speed in first medium
v2 = speed in second medium
sin i = angle in first medium
sin r = angle in second medium

  • Angles are always measured to the normal

Electric Field

E = Electric field (N/C, V/m)
F = Force (N)
q = charge (C)

Ohm’s Law

R = resistance (W)
V = voltage (V)
I = current (A)

Energy = VIt

Electrical Energy

Energy (J)
V = voltage (V)
I = current (A)
T = time (s)

P=VI

Electrical Power

P = power (W)
V = voltage (V)
I = current (A)

Average Velocity

vav = average velocity (m/s)
r = distance covered (m)
t = time (s)

Average Acceleration

 = average acceleration (ms-2)
dv = change in velocity (m/s)
dt = change in time (s)

Newton’s Second Law

 = sum of all forces (N)
m = mass (kg)
 = acceleration (ms-2)

Kinetic Energy

Ek = kinetic energy (J)
m= mass (kg)
v = speed (m/s)

Momentum

P = momentum (Ns, kgm/s)
m = mass (kg)
v = velocity (m/s)

Impulse

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

Universal Gravitation

F = force (N)
G = universal gravitation constant (6.67 X 10-11 Nm2 kg-2)
m1 = mass of body 1 (kg)
m2 = mass of body 2 (kg)
d = separation between the two bodies (m)

Kepler’s Third Law

r = radius of motion (m)
T = period of motion (s)
G = universal gravitation constant (6.67 X 10-11 Nm2 kg-2)
M = mass of system (kg)
Physics Formulae

Gravitational Potential Energy

Ep = Potential energy
G = universal gravitation constant (6.67 X 10-11 Nm2 kg-2)
m1 = mass of body 1 (kg)
m2 = mass of body 2 (kg)

r = separation between the two bodies from infinity to r (m)
Formulae Physics

Gravitational Force

F = force (N)
M = mass (kg)

g = gravitational constant at the surface of the Earth 9.81 ms-2
Physics Formulae

Newtons’ Laws of Motion

ux = initial speed in x direction (m/s)
vx = final speed in x direction (m/s)
uy = initial speed in y direction (m/s)
vy = final speed in y direction (m/s)
a = constant acceleration (ms-2)
dx, dy = change in displacement (m)

t = time (s)
Physics Formulae Kepler’s third law

r = radius of motion (m)
T = period of motion (s)
G = universal gravitation constant (6.67 X 10-11 Nm2 kg-2)

M = mass of system (kg)
Relativistic Length Contraction

Lv = apparent length (m)
Lo = “rest” length (m)
v = relative velocity (m/s)

c = speed of light (3 X 108 m/s)
Physics Formuale Relativistic time dilation

tv = apparent time (s)
to = “rest” time (s)
v = relative velocity (m/s)

c = speed of light (3 X 108 m/s)
Magnetic force on a current-carrying wire of length l in a magnetic field
F = force (N)
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 10-7 NC-1m-1)
* torque t =torque (Nm)
F =force (N)
d=distance (m)

torque on a coil immersed in a magnetic field

t =torque (Nm)
n =number of turns of coil
B=magnetic field (T)
I = current (A)
A = area of coil immersed in magnetic field (m2)

cos Q=angle between the coil and the magnetic field
Transformer equation

Vp = primary voltage (V)
Vs = secondary voltage (V)
Np = number of turns in the primary coil

Ns = number of turns in the secondary coil
Magnetic force on a charge in a magnetic field

F = force (N)
q = charge (C)
v = velocity (m/s)
B = magnetic field (T)

Sin Q = angle between the velocity and the magnetic field
Electric Field

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

d = distance (m)
Energy of a Photon

E = Energy (J)
h = Planck’s constant 6.626 X 10-34 Js

f = frequency (Hz)
*

Wave Equation

c = speed of light 3 X 108 m/s
f = frequency (Hz)

l = wavelength (m)