Electrical Circuits

Electrical Circuit• Closed path through which

charge can flow

• A Circuit needs:1. Source of energy (voltage)2. Conductive path for charge to flow3. Source of resistance (device to do

work)

Batteries• Provide the energy (voltage) for

charge to flow in a circuit– Have (+) and (-) terminals

Dry cell• Series of chemical reactions

causes electrons to flow and accumulate at the (-) terminal– Used in portable electronics

+ terminal

- terminal

Wet Cell• Has 2 connected metal plates

submerged in an electrolyte: solution that conducts electricity

• Ex: Car battery

Circuit Diagrams• Use symbols to represent parts

of a circuit

• Shows one or more complete paths that charge can flow

Current flow

+-

Current always flows from positive (+) to negative (-) battery terminal

Battery

Series Circuits• Charge has only one path to flow• If one device stops working they

all stop working!• Viewing series circuit

Series Circuits• Adding light bulbs to a series

circuit increases resistance– CURRENT DECREASES, BULBS

BECOME DIMMER

Parallel Circuits• Circuit with two or more paths

for current to flow• If one device stops working the

rest continue to work!

Parallel Circuits• Viewing Parallel Circuit

• Homes and buildings are wired in parallel

• Bulbs shine brighter in parallel than series– All Directly connected to battery

Parallel circuits• Current in branch depends on

resistance– More current flows through the

path of lowest resistance

•Voltage is same across each branch