Abhishek DhawanAssistant Manager – Editorial Content
What are Physics Symbols?
In physics, different notations are used to signify a quantity under consideration. The denotations illustrate the term being described as a symbol.
Some physics terms are easily understood (like “d” for distance), while others are slightly ambiguous (like “c” for the speed of light). Here is the list of the most frequently used units in science, along with the commonly used symbols. It is essential to remember that different symbols, sometimes, symbolize/describe the same quantity.
List of Physics Symbols
| Symbol |
Quantity/ Coefficients |
S.I Unit |
|---|---|---|
| r |
Radius, the radius of curvature |
Meter |
| s |
Displacement |
Meter |
| d |
Distance |
Radian |
| θ, φ |
Angular displacement, angular separation, the rotational angle |
Meter |
| x, y, z |
Cartesian coordinates |
Unitless |
| î, ĵ, k̂ |
Cartesian unit vectors |
Unitless |
| r, θ, φ |
Spherical coordinates |
Meter/Radian |
| r̂, θ̂, φ̂ |
Spherical unit vectors |
Unitless |
| r, θ, z |
Cylindrical coordinates |
Meter/Radian |
| r̂, θ̂, ẑ |
Cylindrical unit vectors |
Unitless |
| n̂ |
Normal unit vector |
Unitless |
| t̂ |
Tangential unit vector |
Unitless |
| h |
Height, depth |
Meter |
| ℓ, L |
Length |
Meter |
| t |
Time |
Second |
| D |
Diameter |
Meter |
| C |
Circumference |
Meter |
| A, A |
Area |
Square meter |
| V |
Volume |
Cubic meter |
| t |
Time, duration |
Second |
| T |
Periodic time |
Second |
| τ |
Time Constant |
Second |
| f |
Frequency |
Hertz |
| ω |
Angular frequency |
Radian per second |
Symbols Used in Modern Physics
| Symbol |
Quantity/Coefficients |
S.I Unit |
|---|---|---|
| D |
Dose/ dose absorbed |
gray |
| t1⁄2 |
Half-life |
Second |
| ψ(r,t), ψ(r)φ(t) |
Wave function |
Unitless |
| Φ |
Work function |
Joule |
| H |
Effective dose |
Sievert |
| Γ |
Lorentz factor/Lorentz gamma |
Unitless |
Physics Symbols to Represent Physical Quantities in Mechanics
| Symbol |
Quantity |
S.I Unit |
|---|---|---|
| v |
Velocity, speed |
meter per second |
| a |
Acceleration |
meter per second squared |
| ac |
Centripetal/Centrifugal acceleration |
meter per second squared |
| g |
Acceleration due to gravity |
meter per second squared |
| m |
Mass |
Kilogram |
| F |
Force |
Newton |
| Fg /W |
Force due to gravity/Weight |
Newton |
| Fn, N |
Normal force, normal |
Newton |
| Ff |
Force of friction |
Newton |
| µ |
Coefficient of friction |
Unitless |
| p |
Momentum |
Kilogram meter per second |
| J |
Impulse |
Newton second |
| E |
Energy |
Joule |
| K |
Kinetic energy |
Joule |
| U |
Potential energy |
Joule |
| Vg |
Gravitational potential |
Joule per kilogram |
| η |
Efficiency |
Unitless |
| P |
Power |
Watt |
| ω |
Rotational speed, rotational velocity |
Radian per second |
| α |
Rotational acceleration |
Radian per second squared |
| τ |
Torque |
Newton meter |
| I |
Moment of inertia |
Kilogram meter squared |
| L |
Angular momentum |
Kilogram meter squared per second |
| H |
Angular impulse |
Newton meter second |
| k |
Spring constant |
Newton per meter |
| p |
Pressure |
Pascal |
| σ |
Stress |
Pascal |
| τ |
Shear stress |
Pascal |
| ρ |
Density, volume mass density |
Kilogram per cubic meter |
| σ |
Area mass density |
Kilogram per square meter |
| λ |
Linear mass density |
Kilogram per meter |
| FB, B |
Buoyancy |
Newton |
| qm |
Mass flow rate |
Kilogram per second |
| qV |
Volume flow rate |
Cubic meter per second |
| FD, R |
Drag or air resistance |
Newton |
| CD |
Drag coefficient |
Unitless |
| η |
Viscosi |
Pascal-second |
| ν |
Kinematic viscosity |
Square meter per second |
| Ma |
Mach number |
Unitless |
| Re |
Reynolds number |
Unitless |
| Fr |
Froude number |
Unitless |
| E |
Young’s modulus of elasticity |
Pascal |
| G |
Shear modulus of rigidity |
Pascal |
| K |
The bulk modulus of compression |
Pascal |
| ε |
Linear strain |
Unitless |
| γ |
Shear strain |
Unitless |
| θ |
Volume strain |
Unitless |
| γ |
Surface tension |
Newton per meter |
Physics Symbols in Class 11
This concept is taught under the chapter units and measurements. You will learn about the units of different physical quantities. The weightage of this chapter is 5 marks.
Illustrated Examples
1) G denotes which law of physics?
Answer - The gravitational constant is the basic element in Newton's fundamental law of gravity, usually denoted by G.
2) What is Q?
Answer - Q is the symbol used to denote "charge," thus n is an integer (positive or negative), and e is an electrical charge, 1.60 x 10-19 Coulombs.
3) What does V mean?
Answer - V stands for volts. Volt is the derived unit for electric potential and electric potential difference.
FAQs on Physics Symbols
Q: Answer the following: (a)You are given a thread and a meter scale. How will you estimate the diameter of the thread? (b)A screw gauge has a pitch of 1.0 mm and 200 divisions on the circular scale. Do you think it is possible to increase the accuracy of the screw gauge arbitrarily by increasing the number of divisions on the circular scale? (c) The mean diameter of a thin brass rod is to be measured by vernier calipers. Why is a set of 100 measurements of the diameter expected to yield a more reliable estimate than a set of 5 measurements only?
A: (a) We require a small cylindrical object on which the thread can be wrapped. Wind the thread in a circular fashion on to the cylinder so that the thread forms a coil. If L is the length of the thread and n is the number of turns, then the diameter D of the thread can be expressed as D = L/n
- (b) The least count of the screw gauge = Pitch / number of divisions on the circular scale = 1/200 = 5 X 10-3
By increasing the number of turns on the circular scale, when denominator increases, the least count will increase and the accuracy will increase. However, when the number of turns increases, there may the problem of readability of the scale.
- (c) Taking 100 measurements, instead of 5 will reduce the probability of error and the observation will be more accurate.
Q: What is δ in physics?
A: In mechanics, delta-v is a calculation of transition in velocity. Delta is the main mathematical symbol used to denote transition.
Q: What is the significance of the symbol n in physics?
A: The newton is the SI unit of power. In technical literature, the word newton(s) is sometimes abbreviated N.
Q: What does r in physics mean?
A: Resistance is R. R = molecular gas constant.
Q: What does T stand for in physics?
A: t is typically used for time, but T is used as a temperature symbol.
Q: What is the C in physics?
A: The speed of light, defined as c, is a significant physical constant in many fields of physics.
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