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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.
We had an ice storm a few years back and there were major power outages all over town. It seemed like everyone was buying an electric current generator. However, these appliances can be very dangerous, and we didn’t recommend that people use them to power the whole “grid” in the house. If the power came back on while the generator was plugged into the house, it could create real problems.
Even today, I don’t recommend these devices to anyone except people who work in the power industry or electricians who really understand how they work. At minimum, I would suggest you buy a small, portable unit that will power a few appliances in your house—like a heater for example, but don’t try to power up the whole house with a backup generator. You can easily start a fire.
One of the most common misconceptions about electrical current that people have is the harm that can be caused by Alternating Current versus Direct Current. In other words, people mistakenly think that Alternating Current (AC) is more harmful than Direct Current (DC). However, this is not necessarily true.
AC cycles, so while it can create a muscle spasm if you grab hold of a live wire, the current will cycle down to zero, giving you a chance to free yourself. DC current does not cycle. If you grab hold of DC current—in sufficient voltage—it will be like a bulldog. It’ll keep delivering it’s “bite” and possibly cause permanent harm.
Of course, DC usually doesn’t get delivered in very high voltages (you find it in batteries) so that kind of makes it less harmful, but the nature of the current itself is not necessarily less harmful.