That voltage is always present and when an electrical load becomes part of the circuit (by plugging in an appliance, for example), that voltage makes current flow through the circuit.Įlectric generators move magnets near coils of wires to create the voltages on the electrical grid.ĭC generation creates voltages using the energy from light in photovoltaic cells, or the energy from chemical reactions, usually inside batteries, and even temperature differences by using thermocouples. The voltage exists whether the charge is present or not.Īn electrical outlet in a house has 120 V (in Canada and the US) across the two holes. Electromotive force is whatever keeps picking the ball up and putting it back on the table (that's what drives the flow of balls falling off of the table).Įlectrical energy is the energy released when a charge 'falls' through a potential difference (voltage). The height times the acceleration due to gravity ( g) gives the total energy that transforms into kinetic energy should the ball fall from that height. Gravitational potential energy is the energy that a ball stores while sitting on a table. This relationship between voltage and current is given by Ohm's law. The specific name for the source of energy that creates the voltage to make current flow is electromotive force. Voltage generates the flow of electrons ( electric current) through a circuit. For convenience, the Earth is almost always defined to be 0 V (in physics classes 0 V is often taken to be the potential at the point infinitely far away, but that isn't useful in electronics). Voltage always depends on some reference point that is defined to be 0 V. One single point does not have a voltage, since voltage is defined as the energy difference between two points.
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