http://www.ck12.org Chapter 5. Energy
5.71 Electric Circuits
- Define electric circuit.
- Describe the parts of an electric circuit.
- Show how to represent a simple electric circuit with a circuit diagram.
Jose made this sketch of a battery and light bulb for science class. If this were a real set up, the light bulb wouldn’t
work. The problem is the loose wire on the left. It must be connected to the positive terminal of the battery in order
for the bulb to light up.
Q:Why does the light bulb need to be connected to both battery terminals?
A:Electric current can flow through a wire only if it forms a closed loop. Charges must have an unbroken path to
follow between the positively and negatively charged parts of the voltage source, in this case, the battery.
Electric Circuit Basics
A closed loop through which current can flow is called anelectric circuit. In homes in the U.S., most electric circuits
have a voltage of 120 volts. The amount of current (amps) a circuit carries depends on the number and power of
electrical devices connected to the circuit. Home circuits generally have a safe upper limit of about 20 or 30 amps.
Parts of an Electric Circuit
All electric circuits have at least two parts: a voltage source and a conductor. They may have other parts as well,
such as light bulbs and switches, as in the simple circuit seen in theFigure5.156. To see an animation of a circuit
like this one, go to: http://www.rkm.com.au/animations/animation-electrical-circuit.html