Units are denoted by an asterisk. Dimensions and values of constants are in parentheses.
See also the NIST pages on constants, units and uncertainty.
| a, A | acceleration (length / time 2), atomic mass (total number of protons and neutrons in an atom) |
| A | Amperes* (electric current = C / s), Angstroms* (length = 10 - 10 m), amplitude (length) |
| b | intercept of a linear graph, drag coefficient (mass / time) |
| B | magnetic field (force / current) |
| c | speed of light (2.998 x 10 8 m / s), specific heat (energy / mass x temperature), concentration (number / volume), speed of sound |
| cal | calories* (energy = 4.186 J) |
| cc | cubic centimeter |
| c g | group velocity |
| c p | phase velocity |
| C | Celsius* (temperature), Coulombs* (electric charge), capacitance (charge / electric potential), heat capacity (energy / temperature), concentration |
| Cal | kilocalories* (energy) |
| Ci | Curie* (unit of radiation, equivalent to 3.7 x 10 10 decays / s) |
| d | distance |
| D | diffusion constant (area / time) |
| db | decibels (relative intensity) |
| e | electron, charge of an electron (1.602 x 10 - 19 C) |
| eV | electron Volts* (energy = 1.602 x 10 - 19 J) |
| E | energy (force x length, mass x velocity 2), electric field (force / charge) |
| f | frequency (1 / time), focal length |
| f, F | force (mass x acceleration) |
| F | flow (volume / time), Farads* (capacitance = C / V), Fermi* (length = 10 - 15 m) |
| g | grams* (mass), acceleration due to gravity (9.81 m / s 2); sometimes centrifugal acceleration |
| G | Newton's constant (6.673 x 10 - 11 N m 2 / kg 2), Gauss* (magnetic field = |
| 10 - 4 T), free energy | |
| h | height, Planck's constant (angular momentum = 6.626 x 10 - 34 J s), latent heat (energy / mass) |
| hr | hours* (time = 3600 s) |
| H | enthalpy (energy) |
| Hz | Hertz (1 / s) |
| I | moment of inertia (mass x length 2), current (charge / time), intensity (power / area), image distance |
| J | Joules* (energy = N m), flux (number / area time) |
| k | Boltzmann constant (1.381 x 10 - 23 J / K), spring constant (force / length), thermal conductivity (power / length temperature), wave number (1 / length) |
| (1 / length) | |
| K | kinetic energy, Kelvin* (temperature = C + 273.15) |
| l | length, liters* (volume = 1000 cc), orbital quantum number (dimensionless, denotes angular momentum), mean free path (length) |
| lb | pounds* (weight; 1 kg weighs 2.2 lb) |
| L | angular momentum (momentum x length, moment of inertia x angular velocity) |
| m | mass, meters* (length), slope of a linear graph, magnetic moment (current x area), magnetic quantum number (dimensionless, denotes orientation of angular momentum) |
| me | mass of electron (9.109 x 10 - 31 kg) |
| mn | mass of neutron (1.675 x 10 - 27 kg) |
| mp | mass of proton (1.673 x 10 - 27 kg) |
| mi | miles* (length = 1.61 km) |
| min | minutes* (time = 60 s) |
| mmHg | millimeters of mercury (pressure = 1333 dynes / cm 2) |
| M | molecular weight (mass / mol), magnification (dimensionless) |
| n | numbers of mols (dimensionless), number of loops (dimensionless), neutron, principle quantum number (dimensionless, denotes energy level), index of refraction (dimensionless) |
| N | Newtons* (force = kg m / s 2), number of particles, neutron number (number of neutrons in an atom) |
| N A | Avogadro's number (dimensionless number of objects in a mol = 6.022 x 10 23) |
| O | object distance |
| p | proton |
| P | momentum (mass x velocity), pressure (force / area), power (energy / time) |
| Pa | Pascals* (pressure = N / m 2) |
| q, Q | charge |
| Q | heat (energy) |
| r | radius (length), distance, rate (velocity) |
| R | resistance (potential / current), gas constant (8.31 J / mol K) |
| Re | Reynolds number (dimensionless) |
| s | seconds*, sedimentation coefficient (time), spin quantum number (dimensionless), lens strength (1 / length) |
| S | entropy (energy / temperature) |
| t | time |
| T | Tesla* (magnetic field = N / A), temperature |
| U | potential energy (mechanical, elastic, electrical), internal energy |
| v | velocity (length / time), specific volume (volume / mass) |
| V | velocity, volume (length 3), electric potential (electric field x length), voltage, Volts* (N m / C) |
| W | Watts* (power = J / s), weight (force), work (energy) |
| x, X | horizontal position |
| y, Y | vertical position or depth position in 3D problems |
| z, Z | vertical position in 3D problems, atomic number (number of protons in an atom), valence |
| a | alpha | angular acceleration (radians / time 2), Helium nucleus (2 p + 2 n) | |
| b | beta | electron | |
| D | delta | finite change | |
| d | "d" | instantaneous rate of change | |
| e | epsilon | electrical permittivity (e0 = 8.854 x 10 - 12 F / m), emissivity | |
| (dimensionless), efficiency (dimensionless) | |||
| f | phi | angle | |
| g | gamma | electromagnetic radiation, photon | |
| h | eta | viscosity (Poise = dyne x s / cm 2 = g / cm x s) | |
| k | kappa | dielectric coefficient (dimensionless) | |
| l | lambda | wavelength | |
| m | mu | magnetic permeability (m0 = 4 p x 10 - 7 T m / A) | |
| n | nu | frequency or rate of revolution (1 / time) | |
| q | theta | angle, angular position | |
| r | rho | density (mass / volume), resistivity (resistance x length) | |
| s | sigma | Stefan-Boltzmann constant (5.67 x 10 - 8 W / m 2 K 4) | |
| S | sigma | summation | |
| t | tau | torque (force x length, moment of inertia x angular acceleration), radioactive half-life | |
| w | omega | angular velocity or angular frequency (radians / time) | |
| W | omega | Ohms* (resistance = volt / ampere) |
If you have stumbled on this page, and the equations look funny (or you just want to know where you are!), see the College Physics for Students of Biology and Chemistry home page.
©1996, Kenneth R. Koehler. All Rights Reserved. This document may be freely reproduced provided that this copyright notice is included.
Please send comments or suggestions to the author.