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Name and Symbols of Different Physical Terms, Descriptions and SI Units


Base quantity
Symbol
Description
SI unit
Length
l
The one dimensional extent of an object.
metre (m)
Matter
m
The amount of matter in an object.

kilogram (kg)
Time
t
The duration of an event.
second (s)
Electric current
I
Rate of flow of electrical charge.
ampere (A)
Temperature
T
Average energy per degree of freedom of a system.
kelvin (K)
Amount of substance
n
Number of particles compared to the number of atoms in 0.012 kg of 12C.
mole (mol)
Luminous intensity
L
Amount of energy emitted by a light source in a particular direction.
candela (cd)




Derived quantity
Symbol
Description
SI units
Plane angle
θ
Measure of a change in direction or orientation.
radian (rad)
Solid angle
Ω
Measure of the size of an object as projected on a sphere.
steradian (sr)
Absorbed dose rate

Absorbed dose received per unit of time.
Gy s−1
Acceleration
a
Rate of change of the speed or velocity of an object.
m s−2
Angular acceleration
α
Rate of change in angular speed or velocity.
rad s−2
Angular speed (or angular velocity)
ω or ω
The angle incremented in a plane by a segment connecting an object and a reference point.
rad s−1
Angular momentum
L
Measure of the extent and direction and object rotates about a reference point.
kg m2 s−1
Area
A
The two dimensional extent of an object.
m2
Area density
ρA
The amount of mass per unit area of a two dimensional object.
kg m−2
Capacitance
C
Measure for the amount of stored charge for a given potential.
farad (F = A2 s4 kg−1 m−2)
Catalytic activity

Change in reaction rate due to presence of a catalyst.
katal (kat = mol s−1)
Catalytic activity concentration

Change in reaction rate due to presence of a catalyst per unit volume of the system.
kat m−3
Chemical potential
μ
The amount of energy needed to add a particle to a system.
J mol−1
Molar concentration
C
Amount of substance per unit volume.
mol m−3
Current density
J
Amount of electric current flowing through a surface.
A m−2
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)
Dynamic Viscosity
η
Measure for the resistance of an incompressible fluid to stress.
Pa s
Electric Charge
Q
Amount of electric charge.
coulomb (C = A s)
Electric charge density
ρQ
Amount of electric charge per unit volume.
C m−3
Electric displacement
D
Strength of the electric displacement.
C m−2
Electric field strength
E
Strength of the electric field.
V m−1
Electrical conductance
G
Meausure for how easily current flows through a material.
siemens (S = A2 s3 kg−1 m−2)
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)
Electrical resistance
R
The degree to which an object opposes the passage of an electric current.
ohm (Ω = kg m2 A−2 s−3)
Energy
E
The capacity of a body or system to do work.
joule (J = kg m2 s−2)
Energy density
ρE
Amount of energy per unit volume.
J m−3
Entropy
S
Measure for the amount of available states for a system.
J K−1
Force
F
The cause of acceleration, acting on an object.
newton (N = kg m s−2)
Impulse
p
The cause of a change in momentum, acting on an object.
kg m s−1
Frequency
f
The number of times something happens in a period of time.
hertz (Hz =s−1)
Half-life
t1/2
The time needed for a quantity to decay to half its original value.
s
Heat
Q
Amount of energy transferred between systems due to temperature difference.
J
Heat capacity
Cp
Amount of energy needed to raise the temperature of a system by one degree.
J K−1
Heat flux density
ϕQ
Amount of heat flowing through a surface per unit area.
W m−2
Illuminance
Ev
Total luminous flux incident to a surface per unit area.
lux (lx = cd sr m−2)
Impedance
Z
Measure for the resistance of an electrical circuit against an alternating current.
ohm (Ω = kg m2 A−2 s−3)
Index of refraction
n
The factor by which the speed of light is reduce in a medium.

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)
Irradiance
E
Power of electromagnetic radiation flowing through a surface per unit area.
W m−2
Linear density
ρl
Amount of mass per unit length of a one dimensional object.

Luminous flux (or luminous power)
F
Perceived power of a light source.
lumen (lm = cd sr)
Magnetic field strength
H
Strength of a magnetic field in a material.
A m−1
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)
Magnetic flux density
B
Measure for the strength of the magnetic field.
tesla (T = kg A−1 s−2)
Magnetization
M
Amount of magnetic moment per unit volume.
A m−1
Mass fraction
x
Mass of a substance as a fraction of the total mass.
kg/kg
(Mass) Density (volume density)
ρ
The amount of mass per unit volume of a three dimensional object.
kg m−3
Mean lifetime
τ
Average time needed for a particle to decay.
s
Molar energy

Amount of energy present is a system per unit amount of substance.
J mol−1
Molar entropy

Amount of entropy present in a system per unit amount of substance.
J K−1 mol−1
Molar heat capacity
c
Heat capacity of a material per unit amount of substance.
J K−1 mol−1
Moment of inertia
I
Inertia of an object with respect to angular acceleration.
kg m2
Momentum
p
Product of an object's mass and velocity.
N s
Permeability
μ
Measure for how the magnetization of material is affected by the application of an external magnetic field.
H m−1
Permittivity
ε
Measure for how the polarization of a material is affected by the application of an external electric field.
F m−1
Power
P
The rate of change in energy over time.
watt (W)
Pressure
p
Amount of force per unit area.
pascal (Pa = kg m−1 s−2)
(Radioactive) Activity
A
Number of particles decaying per unit time.
becquerel (Bq = s−1)
(Radioactive) Dose
D
Amount of energy absorbed by biological tissue from ionizing radiation per unit mass.
gray (unit) (Gy = m2 s−2)
Radiance
L
Power of emitted electromagnetic radiation per solid angle and per projected source area.
W m−2 sr−1
Radiant intensity
I
Power of emitted electromagnetic radiation per solid angle.
W sr−1
Reaction rate
r
Measure for speed of a chemical reaction.
mol m−3 s−1
Speed
v
Rate of change of the position of an object.
m s−1
Specific energy

Amount of energy present per unit mass.
J kg−1
Specific heat capacity
c
Heat capacity per unit mass.
J kg−1 K−1
Specific volume
v
The volume occupied by a unit mass of material (reciprocal of density).
m3 kg−1
Spin
S
Intrinsic property of particles, roughly to be interpreted as the intrinsic angular momentum of the particle.
kg m2 s−1
Stress
σ
Amount of force exerted per surface area.
Pa
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
Thermal conductivity
k
Measure for the ease with which a material conducts heat.
W m−1 K−1
Torque (moment of force)
τ
Product of a force and the perpendicular distance of the force from the point about which it is exerted.
N m
Velocity
v
Speed of an object in a chosen direction.
m s−1
Volume
V
The three dimensional extent of an object.
m3
Wavelength
λ
Distance between repeating units of a propagating wave.
m
Wavenumber
k
Reciprocal of the wavelength.
m−1
Weight
w
Amount of gravitation force exerted on an object.
newton (N = kg m s−2)
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)








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