electricity - prince edward island · circuit electricity in this unit, we will cover: ... electric...

Electricity Part 1: Static Electricity

Atoms are made up of charged particles.

Atoms are made of 3 subatomic particles: protons, electrons and neutrons.

Introduction: Atoms

Protons

(+) Charge

Neutrons

(-) Charge

Electrons

No Charge

Introduction: Atoms

Protons

(+) Charge

Neutrons

(-) Charge

Electrons

(-) Charge

Normally, the number of protons (+) equals the number of electrons (-) and there is no charge.

If there are more protons (+) than electrons (-) the material will have a positive charge.

If there are less protons (+) than electrons (-) the material will have a negative charge.

Electrons can leave their atoms.

Electrons can easily move, but protons cannot.

Moving Charges

When a material loses its electrons, it develops a (+)

charge

When a material gains electrons, it develops a (-) charge

Electrons can leave their atoms.

Electrons can easily move, but protons cannot.

Moving Charges

When a material loses its electrons, it develops a (+)

charge

When a material gains electrons, it develops a (-) charge

This causes uncharged objects to become (+) and (-) charged

We say the materials have developed a static charge

-

+

Static Charge When two charged objects are placed near

each other, they exert a force on each other.

If objects have different charges, they attract.

If objects have the same charge, they repel.

Objects can be statically charged in 3 ways:

Charging By Friction

Static Charge

When two objects rub together, one object loses electrons and the other gains electrons.

++- -

+- +

- -

+- -

- ++

+negative

Positive

Objects can be statically charged in 3 ways:

Charging By Contact

Static Charge

When a charged object touches a neutral object, the (-) charges move by direct contact.

++-

- - -

- -

- - -

-

negative

Objects can be statically charged in 3 ways:

Charging By Induction

Static Charge

When (-) charges separate without contact and are then pulled away from an object.

- +- +-

-

- -

+- +- -

+- +-

- +

- +-

Positive

Static Charge Charging by contact explains why you get shocked when you touch a metal object.

When you walk across the carpet, you cause

electrons to move from the carpet to the rubber

soles of your shoes.

This creates a build up of excess electrons,

giving your shoes and your body an overall (-)

charge.

When you touch a conductor, like a metal doorknob, the electrons “jump” over to the metal,

giving you a shock!

- -

- - - - -

- -

Lightning Lightning is simply a large scale version of what happens when you get shocked by a doorknob.

Lightning 1 In a cloud, there are (+) and (-) charges.

There are equal numbers of each.

- +

+

+

+-

- -

Lightning 2 Wind and gravity separate the charges, with the

heavier (-) charges going to the bottom.

++ ++

- - - -

Lightning 3

++ ++

Due to induction, the (-) charges in the cloud repel the (-) charges in the ground to move down.

- - - - - - ++++++

- - - -

Lightning 4

++ ++

++++++

Now the ground has a (+) charge. The (+) charges in the ground attract the (-) charges in the cloud.

- - - -

Lightning 5

++ ++

++++++

When the difference is big enough, the (-) charges move from cloud to ground, causing lightning!

Lightning 6

Any Questions?

Electricity Part 2: Current Electricity

1)  What Is Current? 2)  Electrical Circuits 3)  Types of Circuits 4)  Current 5)  Voltage

Circuit Electricity

In this unit, we will cover:

Static electricity cannot make TVs and light bulbs work.

This is because static electricity only carries a very limited amount of electric charge.

Introduction

To be useful, we need a constant flow of electric charges

This flow is called electric current

Electric current is the flow of electrons through a conductor, such as a wire.

Current

The electrons come from a source like an electric cell, or a battery.

Current

The electrons leave the cell at the negative (-) terminal

Current

The electrons get pushed through the wires along a path

Current

The electrons then return to the cell at the positive (+) terminal

Current

While they flow around the wire, they transfer energy to things

In order for charges to flow, there must be a closed path, or loop.

Electric Circuits

This path is called an electric circuit

Electric current is the flow of electrons through a conductor, such as a wire.

Circuits can either be open or closed:

No continuous path: electrons can’t flow

Open

Continuous path: electrons can flow

Closed

Open and Closed

All circuits have certain basic components:

Electric Circuits

Cell Wires

Switch Device(s)

We draw electrical circuits using simple diagrams.

Drawing Circuits

Circuit Diagram

Circuit Diagrams Circuit diagrams are used to represent the

parts of a circuit in a simple way.

Circuit Symbols

There are 2 major types of simple circuits:

Only 1 path for the current to take.

Series Circuit

Types of Circuits

Each device is wired on a single

path.

There are 2 major types of simple circuits:

Simple to build

Series Circuit

Types of Circuits

If one device stops working, they all do

ADVANTAGES

DISADVANTAGES

There are 2 major types of simple circuits:

More than 1 path for the current to

take.

Parallel Circuit

Types of Circuits

Each device has its own connection

to the cell.

There are 2 major types of simple circuits:

If one device stops working, the others

stay working

Types of Circuits

Complicated to build

DISADVANTAGES

Parallel Circuit ADVANTAGES

Electrons flow through electrical circuits.

Current is the amount of electric charge that flows through a circuit in a given time.

Current

Current is measured in amperes (amps)

Current is measured with a device called an

ammeter

Series

The current changes

depending on the number of cells

The current changes

depending on the number of components

Changing Current

Current In A Series Circuit

In a series circuit, the current is the same every place in the circuit!

4 A ? A

? A

Current In A Parallel Circuit

6 A ? A

? A

? A ? A

In a parallel circuit, the current is the splits up between the different loops

Only 1 path

Series Circuit

Multiple paths

Parallel Circuit

Summary: Current

Current stays same Current splits up

6A 6A

6A 6A 2A 2A 2A

Electrons can only flow if they have energy.

Voltage is a measure of how much energy each electron has in a circuit.

Voltage

Voltage is measured in volts (V)

Voltage is measured with a device called a voltmeter

Parallel

The voltage changes

depending on the number of cells

The voltage changes

depending on the number of components

Changing Voltage

V

V V

Voltage In A Series Circuit

6 V

The 3 bulbs are the same

? V 2 V

V

V

Voltage In Parallel Circuit

6 V

? V

? V

6 V

6 V

Series Circuit Parallel Circuit

Summary: Voltage

Current stays same Current splits up

6A

6A

6A 6A 2A 2A 2A

Voltage splits up Voltage stays same

3V

3V

6V 6V 6V 6V 6V

Any Questions?