# Constants and Units

Watch your units! This can get tricky, because sometimes you are working with molar quantities and other times you are working with individual particles.

## Individual Particles[edit]

For individual particles, remember the Boltzmann Constant: [math]k_{B} = 1.3806488 × 10^{-23}[/math].

Thermal energy per particle, for example, is: [math]\frac{3}{2}k_{B}T[/math], where T is the temperature in Kelvins.

## Molar Quantities[edit]

For molar quantities, you'll be working with the ideal gas constant [math]R[/math]; this is just the Boltzmann constant times Avogadro's number.

Thermal energy per mole of particles, for example, is [math]\frac{3}{2}RT[/math].

## Electromagnetic Quantities[edit]

There are a lot of quantities to keep track of in electromagnetism: charge, voltage, current, power, flux, permeability, susceptibility, reluctance, resistance, capacitance, inductance, impedance...

A table will be added here to help you keep track of their fundamental units and interrelationships.