voltage_electromotive_force - Voltage Electromotive Force...

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Page 1 Voltage - Electromotive Force Electrical current flow is the movement of electrons through conductors. But why would the electrons want to move? Electrons move because they get “pushed” by some external force. There are several energy sources that can force electrons to move. Chemical : Battery Magnetic : Generator Light (Photons) : Solar Cell Mechanical : Phonograph pickup, crystal microphone, antiknock sensor Heat : Thermocouple Voltage is the amount of “push” or “pressure” that is being applied to the electrons. It is anal- ogous to water pressure. With higher water pressure, more water is forced through a pipe in a given time. With higher voltage, more electrons are pushed through a wire in a given time. If a hose is connected between two faucets with the same pressure, no water flows. For water to flow through the hose, it is necessary to have a difference in water pressure (measured in psi) between the two ends. In the same way, For electrical current to flow in a wire, it is neces- sary to have a difference in electrical potential (measured in volts) between the two ends of the wire. A battery is an energy source that provides an electrical difference of potential that is capable of forcing electrons through an electrical circuit. We can measure the potential between its two terminals with a voltmeter. A voltage source water analogy: In any case, electrostatic force actually moves the electrons. It is generally the result of having more electrons in one place than another. Since like charges repel, they all push against each
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This note was uploaded on 04/17/2010 for the course ECE 112 taught by Professor Traylor during the Winter '09 term at Oregon State.

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voltage_electromotive_force - Voltage Electromotive Force...

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