Electrical Circuits

May 18, 1999

Interactions of the moving electrons and the stationary molecules within a conductor resist the current. The resistance is more if the material has few electrons able to move, if the length of the conductor is more, or if the cross-sectional area is less. Resistance makes heat from the electrical energy. Fuses, circuit breakers, lie detectors, light bulbs, and electric heaters use of electrical resistance. 

The loads in a circuit are either conductors or semiconductors. Conductors allow electrons to move almost freely. Semiconductors allow electrons to move with high resistance. Insulators do not conduct any electricity. 
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If the loads of a circuit are in the same line, the currents through the loads are equal. The voltages are split among the loads. This circuit is called a series circuit. A series circuit has higher resistance because there is a longer length. 

If the loads of a circuit are on separate lines, the currents are split among the loads. The voltages are equal. This circuit is called a parallel circuit. A parallel cirrcuit has less resistance, because there is more area. 
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In a series or parallel circuit, the current that goes into a point must equal the current that comes out. Also, the voltages around each circuit loop must add to zero. Otherwise, the electrons would build up somewhere in the circuit.