Series and Parallel Circuits Ingrid Munson & Meghan Campbell Series and Parallel Circuits

Circuits Can either be series or parallel.

Series If you add a resistor (like another light): Total resistance goes UP since all the current has must go through each resistor.

Adding Resistors to Series: Current in the circuit will go DOWN (lights will dim) If you remove a light bulb or one burns out—all go out!

Current in Series Current is the same at all points Use Ohm’s Law to find current using resistance and voltage

Resistance in Series Add up all resistors to get total Total resistance will go up because all of the current must go through each resistor.

Series Circuit Closed electrical circuit that is connected so that the current passes through each circuit element in turn without branching off.

Race Track

Parallel Circuits Have more than one path that the circuit can follow and electrical energy therefore is not shared. Each electrical device can be on or off within the circuit.

Parallel Circuits Cars have many pathways to travel, one might be a five lane freeway, while another is a two lane street. Eventually all cars must return to the service station for more energy.

Parallel Circuits Has at least one point where current divides More than one path for current to flow Paths are also known as branches

Lights in Parallel

Parallel: Total resistance goes down If you add a resistor: Total resistance goes down Total current goes up when you add another path

Removing a Light Bulb If you remove a light bulb or one burns out, the others stay on because the circuit is still closed.

Current in Parallel Current flows into a branching point, the same total current must flow out again Current depends on resistance in each branch

Voltage in Parallel Voltage is the same across each branch – because each branch is on the same wire

Resistance in Parallel Calculate current in each branch based on resistance in each branch by using Ohm’s Law

Batteries in Series and Parallel:

In series—The voltage is increased. Battery Explanation In series—The voltage is increased. In parallel—No change in voltage; these batteries will last longer!

Equations - Series Rt=R1+R2+R3 it=i1=i2=i3 Et=E1+E2+E3

Equations - Parallel Et=E1=E2=E3 it=i1+i2+i3 1/Rt=1/R1+1/R2+1/R3