Unit F

Energy and Motion

Chapter 15

Electricity and Magnetism

Lesson 1: What is Static Electricity?

Electric Charges1. Many of the atoms that make up matter

carry tiny units of electricity called electric charges.

2. There are two kinds of charges: positive and negative charges.

a. Like charges repel or push away each otherb. Unlike charges attract or pull toward each

otherc. Negative charges can move more easily from

one material to another.

Buildup and Discharge1. Static Electricity is the buildup of electric

charges on the surface of an object.

2. Electric Discharge is the loss or release of the built-up negative charges.

a. A bolt of lightning is an example of electric discharge.

Lesson 2: What is Electric Current?

How Charges Move

1. In order for electric charges to be useful, they have to flow.

2. An Electric Current is the continuous flow of electric charges.

Conductors and Insulators1. Conductors are materials that allow

electricity to pass through them easily.a. Examples: Metals (copper, aluminum, gold,

and silver) and water

2. Insulators are materials that DO NOT allow electricity to pass through them easily.

a. Examples: plastic, rubber, glass, air, and wood.

Circuits and Switches

1. An Electric Circuit is the pathway that electric current follows.

2. Two kinds of Circuitsa. Closed Circuits are circuits that are complete

(No breaks in the path).

b. Open Circuits are circuits that are incomplete (A break in the path).

3. A Switch is a device that opens or closes a circuit.

a. When the switch is off the circuit is open (the light is off).

b. When the switch is on the circuit is closed (the light is on)

Two Types of Circuits

1. A Series Circuit is a circuit in which the parts are connected so that the electric current passes through a single path.

2. A Parallel Circuit is a circuit in which the parts are connected so that the electric current passes through more than one path.

a. If you remove one part from the circuit, current can still flow.

Electricity in the Home1. The electric wiring in a house is connected in a

parallel circuits.2. If too much current passes through a circuit, the

wires can overheat.3. A fuse is a device that opens a circuit by melting

or breaking.4. A circuit breaker is a switch that opens when it

overheats.5. An electric cell (battery) is a device that changes

chemical energy into electrical energy.

Lesson 3: What Is a Magnet?

Properties of Magnets1. A Magnet is an object that attracts certain

metals, mainly iron.2. Magnetism is the magnet’s ability to

attract materials.3. Two types of magnets

a. Permanent Magnets keep their magnetism for a long time.

b. Temporary Magnets do not keep their magnetism for a long time.

Magnetic Fields1. The Magnetic Field is the space in which

the force of a magnet can act.a. The force of the magnet is greatest at the

magnetic poles (ends of the magnet)

- Unlike poles attract to each other.

- Like poles repel each other.

Earth As a Magnet1. The Earth acts like a magnet because the

Earth’s center is made mostly of molten iron that produces a magnetic field as the Earth spins.

2. Two types of polesa. Geographic Poles are the ends of the

imaginary line around which the earth rotates.

b. Magnetic Poles are the ends of the earth where a compass needle will point.

Lesson 4: How Do Electromagnets

Work?

Electricity and Magnetism

Electromagnets1. An Electromagnet is a strong temporary

magnet that uses electricity to produce magnetism.

a. The electromagnet is created when an electric current passes through a wire coiled around an iron core.

b. Electromagnets are temporary because they can be turned off and on.

c. Blenders, computer disk drives, and doorbells all have electromagnets.

Motors and Generators

1. A Motor is a device that changes electrical energy into energy of motion.

2. A Generator is a device that uses magnetism to convert energy of motion into electrical energy.