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The 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.

Below is an animation of a series circuit where electrical energy is shown as gravitational potential energy (GPE). The greater the change in height, the more energy is used or the more work is done.

In this animation you should notice the following things:

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.

Ohm's Law may be used in a series circuit as long as you remember that you can use the formula with either partial values or with total values but you can not mix parts and totals.