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Hydroelectric power plants are located in areas where the potential energy from falling water can be harnessed for moving turbines and the generation of power. It may not be an economically viable single source of production where the ability to store the flow of water is limited and the load varies too much during the annual production cycle.
In electronics, other forms of electric current include the flow of electrons through resistors or through the vacuum in a vacuum tube, the flow of ions inside a battery, and the flow of holes within metals and semiconductors. A biological example of current is the flow of ions in neurons and nerves, responsible for both thought and sensory ...
Armature: The power-producing component of an electrical machine. In a generator, alternator, or dynamo, the armature windings generate the electric current, which provides power to an external circuit. The armature can be on either the rotor or the stator, depending on the design, with the field coil or magnet on the other part.
The electric field sends the electron to the p-type material, and the hole to the n-type material. If an external current path is provided, electrical energy will be available to do work. The electron flow provides the current, and the cell's electric field creates the voltage. With both current and voltage the silicon cell has power.
An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC).
A schematic representation of long distance electric power transmission. From left to right: G=generator, U=step-up transformer, V=voltage at beginning of transmission line, Pt=power entering transmission line, I=current in wires, R=total resistance in wires, Pw=power lost in transmission line, Pe=power reaching the end of the transmission line, D=step-down transformer, C=consumers.
Since electric power can flow either into or out of a component, a convention is needed for which direction represents positive power flow. Electric power flowing out of a circuit into a component is arbitrarily defined to have a positive sign, while power flowing into a circuit from a component is defined to have a negative sign. Thus passive ...
By contrast, direct-current indoor incandescent lighting systems, such as Edison's first power station, installed in 1882, had difficulty supplying customers more than a mile away because they used a low voltage (110 V) from generation to end use. The low voltage translated to higher current and required thick copper cables for transmission.