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Electricity

WORD SPLASH

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Huh?? Why did the balloon stick to the wall?

The balloon started out neutral

When we rubbed it against out hair, negative charges

from our hair moved onto the balloon resulting in the

balloon being negatively charged.

Transferring Charges

Hair and wool are materials that

readily give up negative charges

When the negatively charged balloon

is brought near the neutrally charged

wall, the wall become positively

charged

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Opposites Attract The common saying “opposites attract” is fundamental

to why the balloon then sticks to the wall.

Since the balloon is now negatively charged, it is

searching out the positive charges located in the wall

It will also search for the left over positive charges from

our hair (floating hair!)

It works the same way for neutral and positively

charged objects

Static Electricity This phenomenon is called static electricity

When have you experienced static electricity before?

Opposites attract

Likes repel

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Huh? What did you notice from our hand holding

demonstration?

What about with the marbles?

What lesson can we take from this?

Current Electricity Using the materials provided (2 wires, a battery and a

light bulb), try to light the bulb

Share with the class what solutions you discovered

How does this relate to our hand holding demonstration?

Show/explain how you made the materials work in your science journals

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Current Electricity Electricity is the flow of electrons (negative charges)

through a conductor.

Current electricity is produced when negative charges

move along a path (circuit)

Both static and current electricity

involve the movement of negative

charges

Electricity can be Dangerous! Both static and current electricity can be dangerous –

let’s review some basic safety measures

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Static Electricity Safety Do not play outside during a thunderstorm

Lightning often takes the easiest path from the clouds to

the ground.

It is easier for static electricity to go through a person than

to take the long way around and go through the air

It is even easier to travel through a gold club or baseball

bat

Static Electricity Safety Do not take cover under a tall tree during a

thunderstorm

Lightning can hit the top of a tree, travel down the trunk,

and then channel into a person standing under it

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Static Electricity Safety Do not swim during a thunderstorm

Lightning can hit the water and the electricity can channel

into a person in the water

Current Electricity Safety Do not use appliances/devices that have cords with

exposed wires

A short circuit can happen when the outer covering of

wires is worn or when wires touch one another

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Current Electricity Safety Do not overload an electric socket

Heat is produced as electricity passes through wires

If too many wires are plugged into one outlet, the heat

produced can cause a fire

Current Electricity Safety Do not play near power lines

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Current Electricity Safety Never put anything but a plug into a socket

Other objects can conduct electricity and cause a shock

Current Electricity Safety Do not unplug an appliance by pulling the cord. Always

use the plug.

The cord can become damaged and can cause an

electrical shock

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Current Electricity Safety Do not use electrical appliances when you are in or

near water.

Water is a conductor of electricity and if in contact with an

electrical appliance can conduct electricity

Louie

Safety Posters

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Human Uses

In your Science Journals, conduct a survey of human

uses of electricity – where do we use it, how do we use

it and why. How did we do these activities prior to

electricity?

Insulator or Conductor What materials could we test to investigate whether or

not the are capable of conducting electricity?

Try to think of a range of materials – like what we can

recycle, or even what we can’t recycle!

Predict which ones can and which ones can’t

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Insulator or Conductor Using the following materials, investigate materials that

conduct electricity.

Based on your findings, develop a definition for the terms insulator and conductor in your Science Journals and identify what materials would work best to insulate a wire and which would best conduct electricity in a switch.

Switches Electrical switches serve the function of operating

electrical circuits

Think of a circuit like running around a room while always

having to touch the side

When the doors are all closed, you can keep running and

running

When the door is opened, you get stopped because your

hand can’t “jump” the system

By closing an electrical switch, the negative charges

are able to flow through the circuit. When the switch is

opened, the charges can no longer flow.

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Circuits Construct a circuit using one battery and three light

bulbs similar to the system we created before.

Draw and label your circuit in your Science Journal

Predict what will happen if you unscrew one of the light

bulbs. Explain your thinking then test your prediction

Circuits Try to create a circuit that will allow the remaining light

bulbs to stay lit even when one light bulb is removed.

Explain in your Science Journal how you re-designed

the circuit and how it works.

Include a labeled diagram

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Circuits The two types of circuits that were created are called

parallel and series.

Which title belongs to which diagram? Why?

Provide examples of when parallel and series circuits

are used and what would happen if we switched them

for the opposite circuit

These circuits are like climbing a tree using a ladder or

a rope

Brightness Experiment with the materials provided. In your

Science Journals, indicate what happens to the

brightness of the bulbs when you change factors.

Record what you change and what impact it has on the

brightness in a chart

Remember to alter only one

factor at a time to ensure it is a fair

test

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Design project Construct a prototype to solve the following design

challenge:

A construction company has hired you to develop a

security system for new houses. They want a system

that uses an electrical circuit either to set off an alarm,

or to turn on lights if a house is entered illegally. Before

you install the system, you are required to build a

prototype to demonstrate how the system works.

Design project

As a class, develop criteria that address the scientific

components of the task (e.g., complete circuit, switch)

and a variety of other criteria (e.g., appearance,

durability).

Each group will present their prototype to the class,

identifying problems they had in designing and building

it, and explaining how these problems were overcome.

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Electromagnet1. Hold the nail. Wrap the middle section of the wire

tightly around the nail, starting from just below the

head down to just above the point of the nail.

2. Tape one end of the wire to the negative end of the

battery and the other to the positive end.

3. Try to pick up the objects with the nail. Record your

observations.

4. Disconnect the wire from the battery and try to pick up

objects. Record your observations.

5. In your Science Journal, explain your results. Why do

you think this happened?

Electromagnet Each negative charge is surrounded by a force called

an electric field.

When the charge moves, it creates a second field – a

magnetic field

When negative charges are made to flow in a current

through a conductor, such as a piece of metal or a coil

of wire, the conductor becomes a temporary magnet –

an electromagnet

Marshall Brain can explain this to us nicely

Fee free to try his additional experiments at home with

permission from your parents

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Constructing

a Simple

Motor

Constructing a Simple

Generator How to make a very simple generator

If you try this at home, always ask your parents first!

Simple generators can be very useful in our daily lives

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Generators Generators require a source of energy to create a

turbine motion – an electromagnetic source of

electricity

Some generators use water, steam or even wind

Transformation of Energy Energy cannot be created

or destroyed.

It can only be transformed into something new.

If we eat food, we get energy. We use that energy to move, work, play, grow, build…

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Types of Energy Discuss as a class how electrical energy is transformed

into different forms of energy.

Make a list of the various ways it is transformed.

Complete the Journal sentences.

Batteries A battery changes chemical energy into electrical

energy

A dry cell battery is made up of a zinc case with a carbon

rod in the centre. The space between is filled with a

chemical paste. Turning on the switch connects the zinc

and the carbon. A chemical reaction takes place, creating

a circuit through which negative charges can move

Lemons can make simple batteries

A car battery is a wet cell battery made up of layers of

lead. The cas contains water and acid instead of chemical

paste. The lead and the acid cause a chemical reaction

that produces an electrical current.

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Energy Sources:

Hydroelectric Positive Points

Water is a renewable resource

Water is readily available (at least in Canada)

It is cheap to produce

It is relatively pollution free

Negative Points

Land has been flooded to create reservoirs for

hydroelectric plants. As a result, habitats have been

destroyed

Long systems of transmission lines are needed to carry

electricity to where it is needed, and these are expensive

Energy Sources: Coal

Positive Points

Coal is cheap

A large quantity is still available

Other products can be created from coal

Negative Points

Coal causes air and water pollution

Mining has an impact on the environment and is

dangerous for miners

Coal will eventually run out (it is non-renewable)

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Energy Source: Wind

Positive Points

Wind is a renewable energy resource

There are no fuel costs

No harmful polluting gases are produced

Negative Points

Noisy

May spoil the view for people living nearby

A significant amount of land is required

Energy Source: Geothermal

Positive Points

Renewable because once water or steam is used, it can

be pumped back into the ground

It is clean energy – it does not produce greenhouse

gases harmful to the atmosphere

Negative Points

There are potential emissions – Greenhouse gases below

the Earth’s surface could migrate to the surface

Construction of a plant can affect the stability of land

Electricity is still needed to operate heat pumps

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Energy Source: Solar Positive Points

Pollution free – no Greenhouse gas emissions after

installation

Reduces dependence on oil and fossil fuels

Produces power every day – even cloudy days produce

some

Negative Points

Relatively high cost, especially with storage (need

batteries)

Requires a large amount of open space

Fragile materials with relatively low efficiency

Energy Source: Nuclear

Fission Positive Points

Reduces consumption of fossil fuels (coal and oil)

Less expensive

Reliable

Very low Greenhouse gases

Negative Points

Non-renewable

Accidents can release large amounts of radioactive

material into the environment

The waste remains radioactive and hazardous for

thousands of years

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Energy Source: Oil

Positive Points

Small amounts of oil can produce large amounts of

energy

Due to our vast experience with oil technologies, we can

produce ways to utilize oil efficiently

It is reliable

It creates many jobs in Canada

Negative Points

Non-renewable source of energy

Burning oil produces carbon dioxide gas

A lot of oil needs to be imported and is becoming

increasingly expensive