unit 10 lesson 4 what are electric circuits, conductors ... · 10/04/2019 · unit 10 lesson 4...

Unit 10 Lesson 4 What Are Electric Circuits,

Conductors, and Insulators?

Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 10 Lesson 4 What Are Electric Circuits, Conductors, and Insulators?


It’s Shocking!

• Electricity cannot move through all materials.

• Insulators are materials that do not allow electricity to flow. Rubber and plastic are examples of insulators.



It’s Shocking!

• Conductors are materials that allow electricity to flow easily. Metals and some liquids are examples of conductors.



• Electric devices need electricity to work. Electric cords carry electricity to the devices.

• An electric cord contains metal wire. The wire conducts electricity through the cord.

• Electric cords are wrapped in plastic or rubber. These insulators make the cords safe to handle.

It’s Shocking!



It’s Shocking!



A Path to Follow



A Path to Follow

• Electricity must flow in a closed loop.

• A path that electric charges can flow through is called an electric circuit.

• A closed circuit is a complete loop. Electricity can flow through a closed circuit.

• An open circuit is an incomplete path. Electricity cannot flow through an open circuit.



A Path to Follow

• A switch controls the flow of charges by opening and closing the circuit.

• When the switch in a circuit is open, the circuit isn’t complete. Electric charges cannot flow.

• When the switch is closed, electric charges can flow through the circuit.



A Path to Follow



Who Needs a Map?

• In a series circuit, electric charges must follow only one path.

• If any part of a series circuit breaks, the circuit is open. Electric charges cannot flow.



Who Needs a Map?

• Trace the path electric charges follow in this series circuit. What would happen if one of the lightbulbs burned out?



Who Needs a Map?

• In a parallel circuit, electric charges can follow more than one path.

• If any part of a parallel circuit breaks, the charges can still flow along the other parts.



Who Needs a Map?

• Trace the path electric charges follow in this parallel circuit. What would happen if one of the lightbulbs burned out?



Who Needs a Map?



Circuit Overload!• When electric charges flow through conductors,

the conductors get hot.

• If too much charge flows, the conductor can overheat and start a fire.



Circuit Overload!

• Circuits in homes and buildings have fuses and circuit breakers to protect against fires.

• Fuses and circuit breakers are switches. They open automatically if too much charge flows through them.

• When they open, they stop a charge from flowing through the circuit.



Circuit Overload!• A circuit can overload if too many devices are

plugged into it.

• Each device needs a certain flow of electrical charge, or current. Current is measured in amperes, or amps (A).

• If too many amps flow through a circuit, the circuit breaker or fuse opens.

unit 10 lesson 4 what are electric circuits, conductors ... · 10/04/2019 · unit 10 lesson 4...

Documents