Lower
case letters 
Upper
case Letters 
Greek Letters *
and their names

Equation Abbreviation
for a Physical Quantity

Unit symbol

S.I. Prefix and
its value
NB it always precedes a unit symbol

a

A

α

Α

alpha 
A
= area
A = nucleon
number (atomic mass)
a = acceleration
a =
Wein constant a
= alpha particle


a
= atto 
x
10^{18} 
b

B

β

Β

beta 
B
= magnetic flux density
b
= beta particle

B
= bell (sound intensity)
Bq = becquerel (activity) 


c

C

χ

Χ

χ 
C
= capacitance
c = speed of light c = specific heat capacity

^{o}C
= degree Celsius^{ }(temperature) 
c
= centi 
x
10^{2} 
d

D

δ

Δ

δ 
d
= diameter
d = distance
D = distance from screen
to fringe pattern
D = absorbed dose
Δ = change in
δ = little change in

D
= dioptre (power of a lens)
dB = decibel (sound intensity) 
d
= deci
da = deca (or deka) 
x
10^{1}
x 10^{1}

e

E

ε

Ε

ε 
e = charge on an electron
E = energy
E_{k} = kinetic energy
E = electric field strength
E = Young's Modulus
ε = emf
ε = tensile strain
ε_{o} = permittivity of free space

eV
= electron volt (energy) 
E
= exa 
x
10^{18} 
f

F

φ

Φ

phi 
F = force
f = frequency
f = focal length
f_{e} = focal length of eyepiece lens
f_{o} = focal length of objective lens
Φ = flux
φ = work function

F
= farad (capacitance) 
f
= femto 
x
10^{15} 
g

G

γ

Γ

gamma 
g = gravitational field strength
g = acceleration due to gravity
G = gravitational constant
G = conductance
γ = gamma ray 
Gy = gray (absorbed dose) 
G = giga 
x 10^{9} 
h

H

η

Η

eta 
h = height
h = Planck constant
H = dose equivalent>
H = hubble constant
Η = coefficient of viscosity 
H = henry (inductance)
Hz = hertz (frequency) 
h = hecto 
x 10^{2} 
I

I

ι

Ι

iota 
I = current
I_{0} = peak current
I = sound intensity
I = moment of inertia


j

J

θ

Θ

theta 
J = current density
J = moment of inertia
Θ = angle

J = joule (energy) 


k

K

κ

Κ

kappa 
k = Boltzmann constant
k = spring constant 
K = kelvin (absolute temperature)
kg = kilogram (mass) 
k = kilo 
x 10^{3} 
l

L

λ

Λ

lambda 
l
= length
l = specific latent heat
λ = wavelength
λ = decay constant
L = self inductance
L = angular momentum
ln = natural log of
log = log base 10 of

l = litre ( = 1000cm^{3})  volume measurement 


m

M

m

μ

mu 
m = mass
M = magnification
μ = permeability
μ = coefficient of friction 
m = metre (length)
m^{2}= metre squared (area)
m^{3}= metre cubed (volume) 
M = mega
m = milli
μ = micro

x 10^{6}
x 10^{3}
x 10^{6} 
n

N

ν

Ν

nu 
N = number
N_{O} = original number
N_{A} = Avogadro constant
N = number of turns of wire
n = number of moles
n= order of diffraction
n = number of charge carriers per unit volume
n = refractive index 
N
= newton (force or weight) 
n
= nano 
x
10^{9} 
o

O

ο

Ο

omicron 
NOT used for anything  it would too easily be confused with the number zero

p

P

π

Π

pi 
P = power
p = pressure
p = momentum
π = 3.14 
Pa = pascal (pressure) 
p = pico
P = peta 
x
10^{12}
x 10^{15} 
q

Q




Q
= charge
Q = heat
energy Q = quality
factor




r

R

ρ

Ρ

rho 
r = radius
R = resistance
R = molar gas constant
R = reacrion force
ρ = density
ρ = resistivity
rad = radian 



s

S

σ

Σ

sigma 
s = displacement (vector version of distance)
s = slit width
σ = conductivity
σ = tensile stress
σ = Stefan constant
Σ = sum of 
s = second (time)
Sv = sievert (dose equivalent)
S = siemens (conductance) 


t

T

τ

Τ

tau 
t = time
T = temperature
T = period of a waveform
T_{1/2} = half life
T_{E} = effective half life
T_{B} = bilogical half life
T_{P} = physical half life 
T = tesla (magnetic flux density) 
T = tera 
x 10^{12} 
u

U

υ

Υ

upsilon 
u = initial velocity
u = image distance
U = Uvalue
U = internal heat of a system 
u = atomic mass unit (mass at atomic levels) 


v

V




v = velocity
v = final velocity (when used in conjunction with 'u')
v = image distance
V = volume
V = potential difference
V_{0} = peak voltage 
V = volt (electric potential) 


w

W

ω

Ω

omega 
W = work done
ω = angular velocity
w = width of a fringe 
Ω = ohm (electrical resistance)
W = watt(power)
Wb =weber (magnetic flux) 


x

X

χ

Χ

chi 
x = width
X = reactance 



y

Y

ξ

Ξ

xi 
y = height 

y = yocto
Y = yotta 
x 10^{24}
x 10^{24} 
z

Z

ζ

Ζ

zeta 
z = depth
Z = proton number (atomic number) 

z = zepto
Z = zeta 
x
10^{21}
x
10^{21} 

NOTE
HOW IMPORTANT THE CASE OF THE LETTER IS  LEARN ACCEPTED SYMBOLS
CAREFULLY!!!

NB A
level candidates are required to:
(a) define symbols used in an equation
and
(b) the conditions under which the
equations apply !!!
