When a wire is connected to the terminals of a source, a complete path called a CIRCUIT is formed

An electric circuit provides a complete, closed path for an electric current

Voltage/energy Source

Wires/conductors

Closed circuitMay also include:ResistorsSwitches

SWITCH RESISTORBATTERY/

VOLTAGE

SOURCE

There is only one path for the electrons to take

If one part of the circuit opens, the whole circuit goes out.

*RTotal = R1 + R2 + R3 + …

*Current is the same everywhere in the circuit.

I = V / RT

*Voltage drop across each resistor device is current x resistance. V (drop) = I x R

*Voltage thru battery is sum of voltage drops in circuit. VT = V1 + V2 + V3…

2 ohms

3 oh

ms

4 ohms

3 volts

6 V

*There are separate branches to the circuit

*If there is a break in a parallel circuit, electrons can still move through the other branches

*Separate conductive paths for each bulb /resistor connected to the voltage source

*Any break in a branch, current stops in THAT branch ONLY. Current continues in the other branches.

*1/RTotal = 1/R1 + 1/R2 + 1/R3 + …

*Total Voltage = voltage across each branch

*Vtotal = V1 = V2 = V3 …

*I total = I1 + I2 + I3… (sum of I in all branches)

321

1111

RRRRTotal

2 ohms

3 ohms

4 ohms

3 volts

6 V

2 ohms 2 ohms 2 ohms

*Fuses protect against too much current flowing at once*Inside each fuse is a small strip of metal

If the current becomes too high, the strip of metal melts and breaks the flow of electricity

*When a fuse is blown, a small piece of metal melts if the current becomes too high.

*This causes a break in the circuit, thus stopping the flow of current through the overloaded circuit.

*Circuit breakers have a piece of metal that bends instead of melting and can be reset by changing it back to the on position.

*Series:* The current has only one

loop to flow through.

* Flashlights and some holiday lights

* Amount of current is the same everywhere.

* When any part of a series circuit is disconnected, no current flows through the circuit (open circuit).

*Parallel:* Contain two or more

branches for current to move through.

* The current splits up to flow through the different branches.

* Voltage difference is the same in each branch.

* More current flows through the branches with lower resistance