Electric current is the name for the flow of electrons that makes up the movement of electric charge. Current flows when the voltage on one end of a conductor differs from the voltage on the other end of a conductor. A force that most people deal with nearly every day, flowing current includes lighting, electrical power cords, and the surprising shock that comes from shuffling shoes on carpet in dry weather. This force is measured in units called amperes, also called amps.
A ubiquitous presence in modern life, current can be found flowing through conductors. Conductors include metal like aluminum, copper, and steel, but water can also conduct current. Electric current has proved to be quite useful to people, but it can also pose a danger to life and property. As humans are made up largely of water, this means that they can conduct current as well, which puts them at risk for electric injury if they come into contact with a conductor with an electric charge. They can also be injured if they are in contact with a body of water when it has a charge, even if the water is in the form of a small stream or puddle.
When referring to electric current, it is proper to say that the current flows through a conducting object like a wire or appliance, not in it. Insulation like rubber or ceramic is commonly used to keep current from flowing into nearby conductors. While air acts as insulation for wires that do not have contact with conductors, open-air wires must often be insulated at connecting points like transformers or building entry and exit points.
An ampere, or amp, is the standard unit used to measure electric current. On paper, amperes can be calculated from coulombs by dividing the coulombs by one second. Amperes in electric current are measured using a tool called an ammeter. In equations, electric current is often referred to as I, which is used to stand for the intensity of current before the term was shortened to electric current.
Electric current can cause fire. When it comes in the form of lightning, this force can set fire to foliage and damage buildings. To prevent lightning damage to buildings in areas prone to lightning storms, building owners often install devices called lightning rods that attract the lightning charge to a high metal rod, which redirects and dispels the current underground. Desert electrical storms that produce lightning with no rain can set fire to dry brush that can grow to damage many homes and acres of land.
Voltage measures the energy that is carried by an electric charge. Voltage is measured in volts. The flow of electricity is often compared to the flow of water, and voltage is the electric equivalent of water pressure. The higher the voltage, the faster electrons will flow through the conductor.
