Resistance is measured in ohms ( Ω), or kilo ohms (K Ω, 1,000 ohms). When the resistance increases, less current flows. The relationship is Voltage = Current x Resistance. The resistance of a component or circuit represents how much it resists the electrical pressure (voltage) and limits the flow of electric current. It is a combination of the voltage and current (Power = Voltage x Current). The “ power” of electricity is a measure of how fast energy is moving through a wire. It is expressed in amperes (A) or milliamps (mA, 1/1,000 of an ampere). The electric current is a measure of how fast electricity is flowing in a wire, just as the water current describes how fast water is flowing in a pipe. Notice the “+” and “–” signs on the battery these indicate which direction the battery will “pump” the electricity.
The electrical pressure exerted by a battery or other power source is called voltage and is measured in volts (V). Switches and transistors control the flow of electricity like valves and faucets control water. Devices like LEDs, motors, and speakers use the energy in electricity to do things. Wires carry electricity, like pipes carry water.
Power sources, such as batteries, push electricity through a circuit, like a pump pushes water through pipes. Electricity is the movement of sub-atomic charged particles (called electrons) through a material due to electrical pressure across the material, such as from a battery.
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We only know how to produce it, understand its properties, and how to control it. What is electricity? Nobody really knows.