TEK 5.8 TEK 5.8 (C)(C)

Demonstrate that electricity can flow in a circuit and can produce heat, light, sound and magnetic effects.

Circuit A closed path through which electricity travelsElectric currentThe movement of electricity through an electric circuit (the path).Energy SourceFor electricity to flow through a closed circuit, there must be an energy source, that sends out an electric current.

Important Words to Know

Example: a battery

Watch the circuit below.

If electricity flows through the circuit, the bulbs light up.

If electricity cannot flow through the circuit, the bulbs do not light up.

How was the electrical path

or circuit opened?

By removing one light bulb,the electric circuit was opened, and

no light was produced.

And the “battery” was the source of the

electrical energy, that caused the

bulbs to light up.

So, remember, electrical energy, flowing in a circuit produces “light.”

Besides producing light, electricity

can also produce “heat.”

What is the source of electricity for the toaster to produce the “heat” that toasts the bread?

For the toaster to produce heat, it needs a source of electricity .The toaster must be plugged in to the “wall socket” to get electricity. Electricity comes from the power plant, through wires, to the wall socket.

And, the electricity is transformed (or changed) into “heat” to toast the bread!

Electric current flows from the wall socket, through the wires, and in to the radio. In the radio, the electricity is transformed into “sound.”

Electricity produces, light, heat, and also…“sound!”

“Electromagnets”

So, we know that electricity produces, light, heat, and sound. And it can also

produce “magnetic effects!”HOW?

“Electromagnets”

•A temporary magnet can be made by passing electric current through a wire coiled around an iron bar.

“Electromagnets”

•A junkyard is one place to see an electromagnet in action.

•A crane holding a huge electromagnet can be used to pick up scrap metal when current flows through it. When the crane operator wants to drop the scrap, he or she will simply shut off the current to the electromagnet.

So we know that electricity can flow in

a circuit and produce…

lightheatsoundmagnetic effects

Let’s Review Question #1

1.1. In order to watch the television In order to watch the television below, below, what is the source of electricity what is the source of electricity for this circuit?for this circuit?

A. Battery

B. Magnet

C. Television

D. Wall Outlet

Correct Answer Choice:Correct Answer Choice:

D. Wall OutletThe source of electricity for this electric circuit is the wall outlet. Placing a plug into a wall outlet allows you to get the electricity. (Electricity comes from the power plant to your house.)Electricity travels through the outlet, through the wires in the television’s cord, to the television, and back again.

Incorrect Answer Choice:Incorrect Answer Choice:

A. Battery: There is no battery in this circuit.

A battery is in this kind of circuit.

Incorrect Answer Choice:Incorrect Answer Choice:

B. Magnet: Although there is a magnet inside the TV, it is not the “source” of electricity.

Incorrect Answer Choice:Incorrect Answer Choice:

C. Television: The television is in the circuit, and it changes electricity into light and sound. But it is not the “source” of electricity, like the wall socket.

Source

Let’s Try Question #2

2. Which of the following 2. Which of the following transformstransforms electrical energy to heat electrical energy to heat energy?energy?

A.

B.

C.

D.

Correct Answer Choice:Correct Answer Choice:

B. toaster

Electric current flows into the toaster and passes through coils that heat up. These heated coils toast the bread.

The toaster changes the electricity into heat.

Hint:If you see a plug, you know it needs electricity.

Do you like your bagel toasted?

Incorrect Answer Choice:Incorrect Answer Choice: A. wind turbine

The wind turbine transformswind energy into electricalenergy. It does not involve heat.

Incorrect Answer Choice:Incorrect Answer Choice:

C. flash light

A flash light changes electrical energy into light, not heat.

Incorrect Answer ChoiceIncorrect Answer Choice::

D. fire

A fire makes heat, but it does

not use electrical energy to make the heat.

Let’s Try Question #3

3. One difference between an 3. One difference between an electromagnet electromagnet and a bar magnet is that the and a bar magnet is that the magnetic magnetic field produced by an electromagnet field produced by an electromagnet can __ ? can __ ?

A. be made permanent

B. be turned on and off

C. have two north poles attract

D. be made of materials such as wood

Correct Answer Choice:Correct Answer Choice:

B. be turned on and off

The magnetic field of an electromagnet is a result of the electric current in the wire. Since the electric current can be switched on and off, so can the electromagnet.

Incorrect Answer Choice:Incorrect Answer Choice:

A. be made permanent

Bar magnets stay magnetic for a long time and cannot be turned on and off.

N S

Incorrect Answer Choice:Incorrect Answer Choice:

C. have two north poles

All magnets, including electromagnets have one north pole and one south pole.

Incorrect Answer Choice:Incorrect Answer Choice: D. attract material such as wood

Since wood is not magnetic, it will not be attracted by either a bar magnet or an electromagnet.

(Iron is magnetic, not wood.)

And finally, Question #4

4. Which of the following examples 4. Which of the following examples below below is an energy change that is needed is an energy change that is needed to to listen to a radio? listen to a radio?

A. electricity to sound

B. electricity to light

C. electricity to heat

D. electricity to motion

Correct Answer Choice:Correct Answer Choice:

A. electricity to sound

When the radio is plugged in, electricity is changed into sound energy that travels from the speaker to your ears.

Incorrect Answer Choice:Incorrect Answer Choice:

B. electricity to light

A clock radio does produce light, but to hear a radio, the radio must produce sound.

Incorrect Answer Choice:Incorrect Answer Choice:

C. electricity to heat

The question is asking what is needed to “hear a radio.”

Incorrect Answer Choice:Incorrect Answer Choice:

D. electricity to motion

The question is asking what is needed to “hear a radio.”

In summary, electricity can In summary, electricity can flow in flow in

a circuit and can producea circuit and can produce … … -light-light -heat -heat -sound -sound -magnetic effects -magnetic effects