Circuits

Circuits

• Closed circuit – switch closed, electricity flows

Open Circuit – switch open, no electricity flows

Circuit Diagram

• Circuit diagrams - shortcuts to drawing a circuit

• Circuits are made up of different parts – wires, switches, batteries, &

resistors

Common Circuit Symbols

• Wire

• Battery

• Light bulb

• Resistor

Types of Circuits

• Series Circuits – has only one path– Current is the same everywhere– Voltage decreases as it passes through resistors– If any part circuit is broken, the circuit fails– Ex) Older Christmas lights: if one bulb doesn’t

work, the entire strand doesn’t work.

• Parallel Circuits – has multiple paths for flow– The branches are all independent: If one fails, the

rest of them still work– Voltage and current same across branches– Ex ) Home or school - If one thing stops working,

everything else still works

Short Circuit

• A short circuit is a wire that bypasses a device in a circuit

• Electricity always chooses the path of least resistance

• Wires have virtually no resistance, so it will go through a wire rather than a device

• Short circuiting a battery cause two problems:– Battery gets drained faster– Wire will heat up, possibly melting the insulation,

which could start a fire