19.1. Series Circuits http://www.ck12.org
19.1 Series Circuits
- Describe a series circuit.
- Understand current as it passes through a series circuit.
- Understand voltage drops in a series circuit.
- Understand resistance in a series circuit with multiple resistors.
- Calculate current, voltage drops, and equivalent resistances for devices connected in a series circuit.
Resistors, including electrical appliances, have a particular current at which they operate most effectively and safely,
and excessive current can cause irreparable damage. Therefore, it is important to limit the amount of current that
may pass through a particular electrical circuit. There are a number of safety devices used in electrical circuits to
limit the current; fuses, circuit breakers, and surge suppressors. When fuses, such as those shown above, are placed
in an electrical circuit, all the current must pass through the wire in the fuse.
Series Circuits
Electrical circuits are often modeled by using water in a river. The potential energy of the water is the highest at
the source of the river and decreases as the water flows down the river toward the end. When the water reaches the
ocean, its potential energy has become zero. The circuit shown above has a similar situation. The current in this
circuit is drawn in the direction of the electron flow. It starts at the battery on the left, where electrons leave the
negative terminal and travel around the circuit. Since all of the current travels across each resistor, these resistors are
said to be inseries. A series circuit is one in which all of the current must pass through every resistor in the circuit.
Returning to the water analogy, there is only one riverbed from the top of the mountain to the ocean.