Electrical current is the flow of electrons through a circuit, measured as the rate at which those charges pass a certain point. Current is typically measured in amperes (or amps), as charge over time. The unit of electrical charge is the coulomb, approximately 6.242 times1018electrons. Electrical current, then, is coulombs/second that pass any point within the circuit.
Voltage is required to make electrons move in a current (or a steady flow). It’s a force of potential electrical energy on the electrons, and it can change direction. For example, if one side of a circuit has a positive charge, electrons will be drawn in that direction, and current will flow to that side of the circuit. But if that charge changes, the electrons will move in the opposite direction.
Some materials allow current to pass through them, and some do not. Materials that allow current to flow through them are known as conductors, and those that do not are called insulators. Many types of metal are conductors. Conversely, glass is one of the strongest insulators. Copper is one of the most common conducting materials used for electrical wires and cables.
Each electrical item that requires current has an ideal electrical current that should pass through to power it. Electrical current must be regulated so that the circuit isn’t overrun; a current regulator can keep current steady. Items (such as light bulbs) can burn out if the circuit can’t handle that amount of power. Electrically powered items will typically have an ideal voltage and amp count listed.
Alternating and direct current
There are two types of electrical current: alternating and direct. Alternating current changes the direction of its flow regularly. As mentioned previously, if one side of a circuit changes its charge, the current will begin to flow opposite. Direct current always flows in one set direction.
A standard example of direct current is a battery: electrons flow steadily from one side of the battery to another. Its polarity never changes. Direct current can be better for smaller, battery-operated devices and circuits.
Alternating current transmits electrical energy between buildings. It’s what items receive when they are attached to a wall plug. Sometimes alternating current must be converted to direct current. Computers need alternating current to convert once the electricity comes to the device, so a power supply unit (PSU) makes that conversion.