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)