Ohm's Law

THE OHM'S LAW


PARALLEL CIRCUIT - A parallel circuit has more than one resistor (anything that uses electricity to do work) and gets its name from having multiple (parallel) paths to move along . Charges can move through any of several paths. If one of the items in the circuit is broken then no charge will move through that path, but other paths will continue to have charges flow through them. Parallel circuits are found in most household electrical wiring.


COMPUTING PARALLEL CIRCUIT
The following rules apply to a parallel circuit:

1. The potential drops of each branch equals the potential rise of the source.
2. The total current is equal to the sum of the currents in the branches.
3. The inverse of the total resistance of the circuit (also called effective resistance) is equal to the sum of the inverses of the individual resistances. One important thing to notice from this last equation is that the more branches you add to a parallel circuit (the more things you plug in) the lower the total resistance becomes. Remember that as the total resistance decreases, the total current increases. So, the more things you plug in, the more current has to flow through the wiring in the wall. That's why plugging too many things in to one electrical outlet can create a real fire hazard.

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SERIES CIRCUIT - A series circuit has more than one resistor (anything that uses electricity to do work) and gets its name from only having one path for the charges to move along. Charges must move in "series" first going to one resistor then the next. If one of the items in the circuit is broken then no charge will move through the circuit because there is only one path. There is no alternative route. Old style electric holiday lights were often wired in series. If one bulb burned out, the whole string of lights went off. 


COMPUTATION FOR SERIES CIRCUIT
The following rules apply to a series circuit:

1. The sum of the potential drops equals the potential rise of the source.
2. The current is the same everywhere in the series circuit.
3. The total resistance of the circuit (also called effective resistance) is equal to the sum of the individual resistances.

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REFERENCES:
 http://www.regentsprep.org/Regents/physics/phys03/bparcir/
http://www.regentsprep.org/Regents/physics/phys03/bsercir/default.htm