How Does Electrical Current Flow?

Abstract flowing cables and lights
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For most people, electricity is a mysterious force that somehow magically appears when we flip a light switch or plug in an appliance. Yet, while the science behind the flow of electricity is very complex, the basics of electrical flow, or current, are easy to understand if you learn some key terms and functions. It also helps to compare the flow of electricity through wires with the flow of water through pipes. 

  • 01 of 05


    Atom with electrons orbiting it
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    The flow of electricity through a wire is actually a flow of electrons. An electron is a negatively charged subatomic particle. A wire is a type of conductor, a material that electricity easily travels through. 

    In electrical conductors, current (flow) results from the movement of electrons from one atom to the next. Electrons are either positively or negatively charged. Negative electrons are attracted to positive electrons. At the atomic level, a negative electron will jump from one atom to another. This causes a negative electron to jump from the second atom to a third atom. Then one jumps from the third to a fourth, and so on. This jumping of negative electrons from atom to atom is electrical flow. 

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    Wires connected by blue sparks

    Current is the flow of electrons in a circuit or electrical system. You can also think of current as the quantity, or volume, of water flowing through a water pipe. Electrical current is measured in amperage, or amps.

    Current is broken down into two types: alternating current (AC) and direct current (DC). Generally speaking, AC is the form of electricity that operates lights, appliances, and outlets in your home, while DC is the form of power provided by batteries. For example, your car's electrical system is a DC system. Renewable energy sources, such as solar and hydro-power, produce DC electricity that is converted to AC for use in the home.  

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    Close-Up Of Gauges In Factory
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    Voltage, also known as electromotive force, is the pressure of the electrons in a system. It is similar to water pressure in a pipe. The standard circuits in your home carry either about 120 volts (the actual voltage can vary between about 115–125 volts) or 240 volts (actual range: 230–250 volts). Most light fixtures and outlets are fed by 120-volt circuits, while dryers, ranges, and other large appliances typically use 240-volt circuits. 

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    Volt Ohm Multimeter, analog scale
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    Ohms is the measurement of resistance to the flow of electrons through a conductive material. The higher the resistance, the lower the flow of electrons. This resistance causes a certain amount of heat to be generated in the circuit. The reason that a hair dryer blows hot air, for example, is because of resistance in the internal wiring that produces heat. And it is resistance in the tiny wires of an incandescent light bulb that causes it to heat up and glow with light. 

    In circuit wiring, too much resistance can overload a circuit and cause an electrical fire. Because bad connections caused by things like loose screw terminals and corrosion are likely culprits, electrical connections should be checked regularly to ensure safety in an electrical system.

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  • 05 of 05

    Wattage or Watts

    Electricity meter, close-up (full frame)
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    Wattage indicates the rate at which electrical energy is dissipated, or consumed. The total amount of power consumed by the electrical system in your home is read through the utility company's electric meter. It is measured in kilowatt-hours or 1,000 watt-hours, and that is how you are billed.

    Each electrical device, such as a light fixture or appliance, has a rate of usage measured in watts. For example, a 100-watt light bulb burning for 10 hours uses 1 kilowatt-hour of electricity. 

    Amps, volts, and watts exist in a mathematical relationship to one another, expressed as follows:

    Volts x amps = watts

    If an appliance is rated at 120 volts and 10 amps, it will use up to 1,200 watts when it is running: 120 volts x 10 amps = 1,200 watts.