# The Principles of Electricity

These basic principles of electricity are the basis for the electric devices found in your home and school — things like digital cameras, stereos, flashlights, calculators and portable CD players.

Ohms and Volts

Scientists know that there are ways of measuring electrical quantities. One of these is coulombs per second, a measure of the flow of electrons through a metal conductor or wire. A current of one coulomb per second equals one ampere.

Even materials that conduct electricity resist the flow of electrons. The unit of electrical resistance is an ohm. The pressure needed to make one coulomb per second (one ampere) flow through a conductor having a resistance of one ohm is one volt.

Ohm's Law explains the relationships between voltage (E), resistance (R), and current (I).

In two circuits of equal voltage, the current will be proportionately greater in the circuit of lower resistance. In circuits of equal resistance, the current flowing will be directly proportional to the voltage applied. Current is directly proportional to voltage, inversely proportional to resistance.

I (Amperes) = E (Volts)/R (Ohms)

Also: E = IR or R = E/I

One of the most common electrical measurements you’ll use is the watt, a unit of electrical power: W (Watts) = E (Volts) x I (Amperes).

The quantity of electric charge is measured in coulombs.

Scientists and engineers use their knowledge of electricity to design the latest instruments, tools and devices. And you can put the principles of electricity you’ve just learned to work with the science of batteries brought to you by Energizer.