# Electricity

## Current

An electric current is a flow of electric charge. In electric circuits this charge is often carried by moving electrons in a wire.

## Voltage

an electromotive force or potential difference expressed in volts.

## Resistance

In electricity, a measurement of the difficulty encountered by a power source in forcing electric current through an electrical circuit, and hence the amount of power dissipated in the circuit.

## Power

Electric power is the rate at which electrical energy is transferred by an electric circuit.

## Current, Voltage, Resistance, and Power

The relationship between voltage, current, and resistance is described by Ohm's law. This equation, I = V/R, tells us that the current, I, flowing through a circuit is directly proportional to the voltage, V, and inversely proportional to the resistance, R. In other words, if we increase the voltage, then the current will increase. But if we increase the resistance, then the current will decrease. We saw these concepts in action with the garden hose. Increasing the pressure caused the flow to increase, but getting a kink in the hose increased the resistance, which caused the flow to decrease.