List of Symbols in Physics: Names, Symbols and Units

Content Curator

Symbols in physics are a basic source of written languages and there are a huge number of physical quantities that we use to perform calculations. The way we represent the symbols of quantities varies depending on the kind. Sometimes we use the first letter of the name of a physical quantity in upper case to represent such as ‘A’ for Area, sometimes we use the first letter of the name of a physical quantity in lower case to represent such ‘a’ for Acceleration, sometimes we use completely unrelated characters to represent a physical quantity that is irrelevant to the name such as ‘c’ for representing the speed of light and so on.

Read Important Difference Between Acceleration and Vector

Physics – Symbols of Some Basic Quantities

The names of some basic physical quantities, their symbols, and units are given in the below table.

Name of the Physical Quantity	Symbol used to denote	Name of the Symbol	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Area	A	–	Scalar	m²
Angular Displacement	θ	theta	Scalar	Radian (rad)
Angular frequency	ω	omega	Pseudovector	rad/s
Density	D	–	Scalar	kg/m³
Distance	d, r	–	Scalar	Meter (m)
Length	l	–	Scalar	Meter (m)
Frequency	f, v	–	Scalar	Hertz (Hz)
Heat	Q	–	Vector	Joule (J)
Mass	m	–	Scalar	Kilogram (Kg)
Specific Heat Capacity	c	–	Scalar	Joules per Kg per Kelvin (J kg⁻¹ K⁻¹ )
Speed of light & sound	c	–	Scalar	m/s
Temperature	T	–	Scalar	Kelvin (K)
Time	t	–	Scalar	Seconds (s)
Volume	V	–	Scalar	m³
Wavelength	λ	lambda	Scalar	meter (m)

Check Important Notes for Unit of Acceleration

Physics – Symbols used in Electricity & Magnetism

The names of some physical quantities, their symbols, and units used in electricity and magnetism are given in the below table:

Name of the Physical Quantity	Symbol used to denote	Name of the Symbol	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Area charge density	σ	Sigma	Scalar	Kilogram per square meter
Capacitance	C	–	Scalar	Farad (F)
Charge	q, Q	–	Scalar	Coulomb (C)
Conductivity	σ	Sigma	Scalar	Siemens per meter
Conductance	G	-	Scalar	Siemens per meter
Dielectric constant	\(\varepsilon\)	-	Scalar	(-) Unitless
Electric current	I	-	Scalar	Ampere
Electric Field	E	-	Vector	Newton per coulomb (N C-1)
Electric flux	ΦE	-	Functions as vector	Newton meter squared per coulomb
Electric charge	q, Q	-	Scalar	Coulomb (C)
Energy density	η	-	Scalar	Joule per cubic meter
Electromotive force (emf)	\(\xi\)	Epsilon	Scalar	Volt
Electric Potential Difference	V	–	Scalar	Volt (V)
Electric potential energy	UE	-	Scalar	Joule
Electrostatic force	FE	-	Functions as vector	Newton
Inductance	L	-	Scalar	Henry (H)
Linear charge density	λ	lambda	Scalar	Kilogram per meter
Magnetic force	FB	-	Functions as vector	Newton
Magnetic Field	B	-	Scalar	Tesla
Magnetic flux	ΦB	-	Vector	Weber
Number of turns	N	-	Scalar	(-) Unitless
Poynting vector, intensity	S	-	Functions as vector	Watt per square meter
Resistance/ Electric resistance / internal resistance	R, r	-	Scalar	Ohms (Ω)
Resistivity	ρ	-	Scalar	Ohm-meter (Ω-m)
Turns per unit length	n	-	Scalar	Inverse meter
voltage, electric potential	V	-	Scalar	Volt
Volume charge density	ρ	-	Scalar	Kilogram per cubic meter

Physics – Symbols related to Space and Time

The names of some physical quantities used in Space and Time, their symbols, and units are given in the below table:

Name of the Physical Quantity	Symbol used to denote	Name of the Symbol	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Area	A	-	Functions as both scalar and vector	Square meter
Angular displacement,	θ	-	Functions as both scalar and vector	Meter
Angular separation, the rotational angle	φ	-	Functions as both scalar and vector	Meter
Angular frequency	ω	omega	Scalar	Radian per second
Cartesian coordinates	x, y, z	-	Scalar	Unitless
Cartesian unit vectors	\(\hat{i}\), \(\hat{j}\), \(\hat{k}\)	-	Vector	Unitless
Circumference	C	-	Scalar	Meter
Cylindrical coordinates	r, θ, z	-	Scalar	Meter/Radian
Cylindrical unit vectors	\(\hat{r}\), \(\hat{\theta}\), \(\hat{z}\)	-	Vector	Unitless
Diameter	D	-	Scalar	Meter
Displacement	s	-	Vector	Meter
Distance	d	-	Scalar	Radian
Frequency	f	-	Scalar	Hertz
Height, depth	h	-	Scalar	Meter
Length	\(\ell \), L	-	Scalar	Meter
Normal unit vector	\(\hat{n}\)	-	Vector	Unitless
Periodic time	T	-	Scalar	Second
Radius, the radius of curvature	r	-	Functions as both scalar and vector	Meter
Spherical coordinates	r, θ, φ	-	Scalar	Meter/Radian
Spherical unit vectors	\(\hat{r}\), \(\hat{\theta}\), \(\hat{\Phi}\)	-	Vector	Unitless
Tangential unit vector	\(\hat{t}\)	-	Vector	Unitless
Time Constant	τ	-	Scalar	Second
Time	t	-	Scalar	Second
Time, duration	t	-	Scalar	Second
Volume	V	-	Scalar	Cubic meter

Read Further Relation Between Critical Angle and Refractive Index

Physics – Symbols used in Mechanics

The names of some physical quantities used in Mechanics, their symbols, and units are given in the below table:

Name of the Physical Quantity	Symbol used to denote	Name of the Symbol	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Acceleration	a	-	Vector	meters per second square (m/s2)
Angular acceleration	α	alpha	Vector	radian per second square (rad/s2)
Angular Momentum	L	-	Vector	kg⋅m2s-1
Coefficient of Friction	µ	mu	Scalar	unitless
Energy	E	-	Scalar	Joule (J)
Force	F	-	Vector	Newton (N)
Friction	f	-	Vector	Newton (N)
Kinetic Energy	K	-	Scalar	Joule (J)
Mechanical Work	W	-	Scalar	Joule (J)
Momentum	p	-	Vector	Kg. m/s
Moment of Inertia	I	-	Scalar	kg m2
Period	T	-	Scalar	S or sec
Power	P	-	Scalar	Watt (W)
Potential Energy	U	-	Scalar	Joule (J)
Pressure	p	-	Scalar	Pascal (Pa)
Torque	T	tau	Vector	Newton Meter (Nm)
Velocity	v	-	Vector	m/s
Young’s modulus of elasticity	E	-	Scalar	Pascal (Pa)

Read Also: Potentiometer

Physics – Symbols used in Waves and Optics:

The names of some physical quantities used in Waves and Optics, their symbols, and units are given in the below table:

Name of the Physical Quantity	Symbol used to denote	Name of the Symbol	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Focal length	f	-	Scalar	Meter
Intensity	I	-	Scalar	Watt per square meter
Index of refraction	n	-	Scalar	Unitless
Level	L	-	Scalar	Decibel
Power of a lens	P	-	Scalar	Dioptre
Wavelength	λ	lambda	Scalar	Meter
Wave speed	v, c	-	Scalar	Meter per second

Read More:

Ohm’s Law

Resistors in Series and Parallel Combination

Physics –Symbols related to Thermal Physics

The names of some physical quantities used in Thermal Physics, their symbols, and units are given in the below table:

Name of the Physical Quantity	Symbol used to denote	Name of the Symbol	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Amount of substance	n	-	Scalar	Mole
Coefficient of performance	COP	-	Scalar	Unitless
Emissivity	ε	Epsilon	Unitless	Scalar
Entropy	S	-	Scalar	Joule per kelvin
Heat	Q	-	Scalar	Joule
Heat flow rate	P	-	Scalar	Watt
Internal energy	U	-	Scalar	Joule
Latent heat/specific llatent heat	L	-	Scalar	Joule per kilogram
Linear expansivity, coefficient of thermal expansion	α	Alpha	Scalar	Inverse kelvin
Number of particles	N	-	Scalar	Unitless
Specific heat capacity	c	-	Scalar	Joule per kilogram Kelvin
Temperature	T	-	Scalar	Kelvin
Thermal conductivity	k	-	Scalar	Watt per meter Kelvin
Volume expansivity, coefficient of volume thermal expansion	Β	-	Scalar	Inverse kelvin
Ways, number of identical microstates	w	-	Scalar	Unitless

Read Further: Meter Bridge

Physics – Symbols related to Modern Physics

The names of some basic physical quantities, their symbols, and units are given in the below table.

Name of the Physical Quantity	Symbol used to denote	Name of the Symbol	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Dose / Dose absorbed	D	Scalar	gray
Effective dose	H	-	Scalar	Sievert
Lorentz factor / Lorentz gamma	-	gamma	Scalar	Unitless
Wave function	ψ(r,t), ψ(r)φ(t)	-	Functions as vector	Unitless
Work function	Φ	-	Scalar	Joule

Points to Remember:

We use notations/symbols for each of these quantities to represent.
Symbols are a basic source of written languages such as physics and mathematics.
The way we represent the symbols of quantities or quantities varies on the kind.
We use uppercase letters, lower case letters and some special characters to represent the quantities.
Examples such as Φ, Γ, etc.

Also Read:

Unit of Voltage

Electric Flux

Sample Questions

Ques. How to represent symbols for a quantity? (3 marks)

Ans. The way we represent the symbols of quantities or quantities varies on the kind.

Sometimes we use the first letter of the name of that physical quantity in the upper case.
Sometimes we use the first letter of the name of that physical quantity in the lower case.
Sometimes we use completely unrelated characters to represent a physical quantity that is irrelevant.

Ques. Mention any five physical quantities related to thermal physics? (5 marks)

Ans. The physical quantities are:

Name of the Physical Quantity	Symbol used to denote	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Amount of substance	n	Scalar	Mole
Coefficient of performance	COP	Scalar	Unitless
Emissivity	ε	Unitless	Scalar
Entropy	S	Scalar	Joule per kelvin
Temperature	T	Scalar	Kelvin

Read Further: DC Motor

Ques. Mention any five physical quantities related to space and time? (5 marks)

Ans.

Name of the Physical Quantity	Symbol used to denote	Scalar/ Vector Physical Quantity	S.I Units of the Physical Quantity
Area	A	Functions as both scalar and vector	Square meter
Angular displacement,	θ	Functions as both scalar and vector	Meter
Angular separation, the rotational angle	φ	Functions as both scalar and vector	Meter
Angular frequency	ω	Scalar	Radian per second
Cartesian coordinates	x, y, z	Scalar	Unitless

Read More: Fleming’s Left-Hand Rule

Ques. Mention any five basic quantities along with their S.I units used in Physics? (5 marks)

Ans. The five basic quantities along with their units used in Physics are:

Area (A) - m²
Distance(d) - Meter (m)
Speed(S) - m/s
Heat(H) - Joule (J)
Mass(M) - Kilogram (Kg)

Ques. Define the Index of refraction and mention anyone related laws of refraction? (3 marks)

Ans. Index of Refraction or Refractive Index is calculated as the ratio of the speed of light in a vacuum to that in a second medium of greater density. The refractive index variable is most commonly denoted with the letter n or n' in descriptive text and mathematical equations.

Snell’s law: A relationship between the path taken by a ray of light while crossing the boundary or surface of separation between two contacting substances and the refractive index of each. It asserts that,

n₁/n₂ = sin α₂/sin α₁

Where, n1 and n2 represent the indices of refraction for the two media, and α1 and α2 are the angles of incidence and refraction.

Also Check:

Circuit Diagram

Current Electricity

Ques. Why are symbols important in physics? (4 marks)

Ans. Symbols are important because:

Symbols are a basic source of written languages such as physics and mathematics but inconsistencies in their use become a challenge to students.
In physics, there are a huge number of physical quantities that we use to perform calculations.
It is not easy to use every quantity through the name as a reference.
So, to make it easier to handle we use notations/symbols for each of these quantities to represent.

Ques. What is angular frequency? (3 marks)

Ans. The angular frequency is the angular displacement of any element of the wave per unit time or the rate of change of the phase of the waveform. It is represented with ω (omega).

The formula for angular frequency is ω=2πT=2πf

Where, ω is the angular frequency of the wave.

T is the time period of the wave.

f is the ordinary frequency of the wave.

Physics Related Links:

Lorentz Force	Ampere’s Circuital Law
The Solenoid and The Toroid	Electricity and Magnetism
Electromagnetic Field	The Moving Coil Galvanometer