| Quantity | Description | Unit | Unit abbrev | Symbol |
| Charge | The amount of electrical charge; depends on the number of electrons gained, lost, or flowing; 1 coulomb = 6.25 x 1018 electrons | coulomb | C | Q |
| Potential | Potential energy divided by amount of charge; an electrical "pressure"; often called voltage; sustained potential provided by batteries or generators | volt | V | V |
| Current | The rate of flow of charge in coulombs per second; determined by potential and resistance; potential difference and closed circuit needed for current flow | ampere or amp | A | I |
| Resistance | Opposition to charge flow; depends on structure; circuit devices that provide measured quantities of resistance are resistors | ohm | Ω | R |
| Capacitance | The ability to store charge; stored charge divided by voltage; circuit devices that can store measured quanitites of charge are capacitors | farad (or often microfarad or picofarad) | F | C |
| Power | Rate of doing work or using energy | watt | W | P |
| Energy | Energy supplied to electrons by work of voltage source or energy used by circuit components | joule, electron volt, or kilowatt-hour | J eV kWhr | E |
Useful formulas:
Ohms Law: I = V/R Relates current to voltage and resistance
Electrical Power: P = VI; P = I2R; Relates power consumption to voltage, current and resistance
Capacitance: C = q/V; Relates capacitance (storage ability) to stored charge and voltage
Energy: E = VIt: Relates energy (supplied or used) to voltage, current and elapsed time
Cost of energy used: Find power usage of device in question. The power or current drawn by the device is usually marked on it somewhere. If the current is given, multiply it by the voltage (120 volts for straight household current) to find the power usage in watts. Divide the power in watts by 1000 to get kilowatts. Multiply kilowatts by the number of hours the device is used to get the energy used in kilowatt hours. Multiply this by the cost per kilowatt hour charged by the power company.
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