| Type |
Physical quantity |
Symbol |
Description |
SI unit |
| |
| Base |
Amount of substance |
n |
Number of particles compared to the number of atoms in 0.012 kg of 12C. |
mole (mol) |
| Base |
Electric current |
I |
Rate of flow of electrical charge. |
ampere (A) |
| Base |
Length |
l |
The one dimensional extent of an object. |
metre (m) |
| Base |
Luminous intensity |
L |
Amount of energy emitted by a light source in a particular direction. |
candela (cd) |
| Base |
Mass |
m |
The amount of matter in an object. |
kilogram (kg) |
| Base |
Temperature |
T |
Average energy per degree of freedom of a system. |
kelvin (K) |
| Base |
Time |
t |
The duration of an event. |
second (s) |
| Derived |
(Mass) Density (volume density) |
ρ |
The amount of mass per unit volume of a three dimensional object. |
kg m-3 |
| Derived |
(Radioactive) Activity |
A |
Number of particles decaying per unit time. |
becquerel (Bq = s-1) |
| Derived |
(Radioactive) Dose |
D |
Amount of energy absorbed by biological tissue from ionizing radiation per unit mass. |
gray (Gy = m2 s-2) |
| Derived |
Absorbed dose rate |
|
Absorbed dose received per unit of time. |
Gy s-1 |
| Derived |
Acceleration |
a |
Rate of change of the speed or velocity of an object. |
m s-2 |
| Derived |
Angular acceleration |
α |
Rate of change in angular speed or velocity. |
rad s-2 |
| Derived |
Angular momentum |
L |
Measure of the extent and direction and object rotates about a reference point. |
kg m2 s-1 |
| Derived |
Angular speed (or angular velocity) |
ω |
The angle incremented in a plane by a segment connecting an object and a reference point. |
rad s-1 |
| Derived |
Area |
A |
The two dimensional extent of an object. |
m2 |
| Derived |
Area density |
ρA |
The amount of mass per unit area of a two dimensional object. |
kg m-2 |
| Derived |
Capacitance |
C |
Measure for the amount of stored charge for a given potential. |
farad (F = A2 s4 kg-1 m-2) |
| Derived |
Catalytic activity |
|
Change in reaction rate due to presence of a catalyst. |
katal (kat = mol s-1) |
| Derived |
Catalytic activity concentration |
|
Change in reaction rate due to presence of a catalyst per unit volume of the system. |
kat m-3 |
| Derived |
Chemical potential |
μ |
The amount of energy needed to add a particle to a system. |
J mol-1 |
| Derived |
Current density |
J |
Amount of electric current flowing through a surface. |
A m-2 |
| Derived |
Dose equivalent |
H |
Measure for the received amount of radiation adjusted for the effect of different types of radiant on biological tissue. |
sievert (Sv = m2 s-2) |
| Derived |
Dynamic Viscosity |
η |
Measure for the resistance of an incompressible fluid to stress. |
Pa s |
| Derived |
Electric Charge |
Q |
Amount of electric charge. |
coulomb (C = A s) |
| Derived |
Electric charge density |
ρQ |
Amount of electric charge per unit volume. |
C m-3 |
| Derived |
Electric displacement |
D |
Strength of the electric displacement. |
C m-2 |
| Derived |
Electric field strength |
E |
Strength of the electric field. |
V m-1 |
| Derived |
Electric potential |
V |
The amount of work required to bring a unit charge into an electric field from infinity. |
volt (V = kg m2 A-1 s-3) |
| Derived |
Electrical conductance |
G |
Meausure for how easily current flows through a material. |
siemens (S = A2 s3 kg-1 m-2
|
| Derived |
Electrical resistance |
R |
The degree to which an object opposes the passage of an electric current. |
ohm (? = kg m2 A-2 s-3) |
| Derived |
Energy |
E |
The capacity of a body or system to do work. |
joule (J = kg m2 s-2) |
| Derived |
Energy density |
ρE |
Amount of energy per unit volume. |
J m-3 |
| Derived |
Entropy |
S |
Measure for the amount of available states for a system. |
J K-1 |
| Derived |
Force |
F |
The cause of acceleration acting on an object. |
newton (N = kg m s-2) |
| Derived |
Frequency |
f |
The number of times something happens in a period of time. |
hertz (Hz = s-1) |
| Derived |
Half-life |
t1/2 |
The time needed for a quantity to decay to half its original value. |
s |
| Derived |
Heat |
Q |
Amount of energy transferred between systems due to temperature difference. |
J |
| Derived |
Heat capacity |
Cp |
Amount of energy needed to raise the temperature of a system by one degree. |
J K-1 |
| Derived |
Heat flux density |
φQ |
Amount of heat flowing through a surface per unit area. |
W m-2 |
| Derived |
Illuminance |
Ev |
Total luminous flux incident to a surface per unit area. |
lux (lx = cd sr m-2) |
| Derived |
Impedance |
Z |
Measure for the resistance of an electrical circuit against an alternating current. |
ohm (? = kg m2 A-2 s-3) |
| Derived |
Impulse |
p |
The cause of a change in momentum acting on an object. |
kg m s-1 |
| Derived |
Index of refraction |
n |
The factor by which the speed of light is reduce in a medium. |
1 |
| Derived |
Inductance |
L |
Measure for the amount of magnetic flux generated for a certain current run through a circuit. |
henry (H = kg m2 A-2 s-2) |
| Derived |
Irradiance |
E |
Power of electromagnetic radiation flowing through a surface per unit area. |
W m-2 |
| Derived |
Linear density |
ρl |
Amount of mass per unit length of a one dimensional object. |
M L-1 |
| Derived |
Luminous flux (or luminous power) |
F |
Perceived power of a light source. |
lumen (lm = cd sr) |
| Derived |
Magnetic field strength |
H |
Strength of a magnetic field in a material. |
A m-1 |
| Derived |
Magnetic flux |
Φ |
Measure of quantity of magnetism taking account of the strength and the extent of a magnetic field. |
weber (Wb = kg m2 A-1 s-2) |
| Derived |
Magnetic flux density |
B |
Measure for the strength of the magnetic field. |
tesla (T = kg A-1 s-2) |
| Derived |
Magnetization |
M |
Amount of magnetic moment per unit volume. |
A m-1 |
| Derived |
Mass fraction |
x |
Mass of a substance as a fraction of the total mass. |
kg/kg |
| Derived |
Mean lifetime |
τ |
Average time needed for a particle to decay. |
s |
| Derived |
Molar concentration |
C |
Amount of substance per unit volume. |
mol m-3 |
| Derived |
Molar energy |
|
Amount of energy present is a system per unit amount of substance. |
J mol-1 |
| Derived |
Molar entropy |
|
Amount of entropy present in a system per unit amount of substance. |
J K-1 mol-1 |
| Derived |
Molar heat capacity |
c |
Heat capacity of a material per unit amount of substance. |
J K-1 mol-1 |
| Derived |
Moment of inertia |
I |
Inertia of an object with respect to angular acceleration. |
kg m2 |
| Derived |
Momentum |
p |
Product of an object's mass and velocity. |
N s |
| Derived |
Permeability |
μ |
Measure for how the magnetization of material is affected by the application of an external magnetic field. |
H m-1 |
| Derived |
Permittivity |
ε |
Measure for how the polarization of a material is affected by the application of an external electric field. |
F m-1 |
| Derived |
Plane angle |
θ |
Measure of a change in direction or orientation. |
radian (rad) |
| Derived |
Power |
P |
The rate of change in energy over time. |
watt (W) |
| Derived |
Pressure |
p |
Amount of force per unit area. |
pascal (Pa = kg m-1 s-2) |
| Derived |
Radiance |
L |
Power of emitted electromagnetic radiation per solid angle and per projected source area. |
W m-2 sr-1 |
| Derived |
Radiant intensity |
I |
Power of emitted electromagnetic radiation per solid angle. |
W sr-1 |
| Derived |
Reaction rate |
r |
Measure for speed of a chemical reaction. |
mol m-3 s-1 |
| Derived |
Solid angle |
Ω |
Measure of the size of an object as projected on a sphere. |
steradian (sr) |
| Derived |
Specific energy |
|
Amount of energy present per unit mass. |
J kg-1 |
| Derived |
Specific heat capacity |
c |
Heat capacity per unit mass. |
J kg-1 K-1 |
| Derived |
Specific volume |
v |
The volume occupied by a unit mass of material (reciprocal of density). |
m3 kg-1 |
| Derived |
Speed |
v |
Rate of change of the position of an object. |
m s-1 |
| Derived |
Spin |
S |
Intrinsic property of particles roughly to be interpreted as the intrinsic angular momentum of the particle. |
kg m2 s-1 |
| Derived |
Stress |
σ |
Amount of force exerted per surface area. |
Pa |
| Derived |
Surface tension |
γ |
Amount of work needed to change the surface of a liquid by a unit surface area. |
N m-1 or J m-2 |
| Derived |
Thermal conductivity |
k |
Measure for the ease with which a material conducts heat. |
W m-1 K-1 |
| Derived |
Torque (moment of force) |
T |
Product of a force and the perpendicular distance of the force from the point about which it is exerted. |
N m |
| Derived |
Velocity |
v |
Speed of an object in a chosen direction. |
m s-1 |
| Derived |
Volume |
V |
The three dimensional extent of an object. |
m3 |
| Derived |
Wavelength |
λ |
Distance between repeating units of a propagating wave. |
m |
| Derived |
Wavenumber |
k |
Reciprocal of the wavelength. |
m-1 |
| Derived |
Weight |
w |
Amount of gravitation force exerted on an object. |
newton (N = kg m s-2) |
| Derived |
Work |
W |
Energy dissipated by a force moving over a distance scalar product of the force and the movement vector. |
joule (J = kg m2 s-2) |
