Unit 10 Lesson 3 Electric circuits

Unit 10 Lesson 3 Electric circuits

Rubber and plastic are used in protective clothing that do not allow electric charges to flow through them. A material that does not allow electric charges to flow through them is called an insulator.

A material that easily allows electric charges to pass through it is called a conductor.

electrical appliances work when electric charge flows through them. The part that carry electric charges are made from conductors. Insulators are wrapped around the conductor so it's safe to touch.

Multiple Choice

Why are conductors used in electrical appliances?

• We need electricity to flow through them to work.

• They make the appliances safe to touch.

Multiple Choice

Why do we use insulators in electrical appliances?

• They make electrical charges flow easily.

• They make them safe to touch.

Multiple Choice

The metal part of the wire is the ....

• conductor

• insulator

Multiple Choice

The plastic or rubber part of the wire is the...

• conductor

• insulator

A circuit is a path along which electric charges can flow. For an electrical device to work, the circuit must form a complete loop.

A closed circuit is a complete loop.

An open circuit is not a compete loop.

Multiple Choice

If the filament in a light bulb is broken the circuit will be

• open and not work.

• closed and will light up

In a series circuit, electric charges must follow in a single path. The charged particles move from the battery's positive terminal to its negative terminal.

Multiple Choice

What happens if a light bulb in a series circuit burns out?

• All of the lights on the circuit will not work.

• Just the light that is broken will not light up

A circuit with several different paths for the charges to follow is called a parallel circuit. If one part of the circuit breaks, the charges can still flow along the other parts.

Fuses and circuit breakers are switches that work automatically. They open if charge flows too quickly through the circuit. The flow stops and the wires cool. This prevents a fire.

A circuit overload takes place when there are too many devices on one circuit. Each device needs a certain amount of charge to work. This flow of charge, or current is measured in amps.

Circuit breakers open when the number of amps is greater than a certain value. If the value for the breaker is 15 amps then the breaker will open if all plugged devices draw more than 15 amps.