# series and parallel circuits

## series circuit

A circuit that consists of one loop is called a series circuit. You can see a simple series circuit below. If a series circuit is interrupted at any point in its single loop, no current can flow through the circuit and no devices in the circuit will work. In the series circuit below, if one light bulb burns out, the other light bulb wont work because it wont receive any current. Series circuits are commonly used in flashlights. Q: If one light bulb burns out in this series circuit, how can you tell which bulb it is? A: It may not be obvious, because neither bulb will light if one is burned out. You can tell which one it is only by replacing first one bulb and then the other to see which replacement results in both bulbs lighting up.

## one loop or two

An electric circuit consists of at least one closed loop through which electric current can flow. Every circuit has a voltage source such as a battery and a conductor such as metal wire. A circuit may have other parts as well, such as lights and switches. In addition, a circuit may consist of one loop or two loops.

## parallel circuit

A circuit that has two loops is called a parallel circuit. A simple parallel circuit is sketched below. If one loop of a parallel circuit is interrupted, current can still flow through the other loop. In the parallel circuit below, if one light bulb burns out, the other light bulb will still work because current can bypass the burned-out bulb. The wiring in a house consists of parallel circuits.

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

all electric circuits consist of at least one closed loop.

``````-->  a. true

b. false
``````

what happens if a one-loop circuit is interrupted at any point?

``````a) no current will flow through the circuit.

b) no devices in the circuit will work.

c) the current will flow more slowly through the circuit.

-->  d) two of the above
``````

series circuits are no longer in use any more.

``````a. true

-->  b. false
``````

what happens if one loop of a two-loop circuit is interrupted at any point?

``````-->  a) current will still flow through the other loop.

b) current will stop flowing through the other loop.

c) the other loop will become overloaded and burn out.

d) two of the above
``````

the wiring in a house consists of parallel circuits.

``````-->  a. true

b. false
``````

## diagram questions

No diagram questions associated with this lesson