Unit 3: Electricity

Intro: Bill Nye Video on Static Electricity– Write down 5 things you learned from the video.

For homework: Write down your response to the following statement– ‘Electricity is more important now than it was in the past’. Do you agree/disagree with this statement? Explain.

Title Page: Create a title page for Unit 3: Electricity.

What is electricity?

• Electricity is a mysterious force. We can’t see it like we see the sun. We can’t hold it like we hold coal. We know when it is working, but it is hard to know exactly what it is. Before we can understand electricity, we need to learn about atoms.

WHAT ARE ATOMS?• Everything is made of atoms—every star,

every tree, every animal. Even you and I are made of atoms. The air and water are, too.

• Atoms are the building blocks of the universe. They are very, very tiny particles. Millions of atoms would fit on the head of a pin.

• All matter is made up of atoms. Atoms are made up of smaller particles called electrons, which are negatively charged. These electrons orbit around a positively charged nucleus.

ATOMS ARE MADE OF EVEN SMALLER PARTICLES• An atom looks like the sun withthe planets spinning around it. The center is called the nucleus. It is made of tiny protons and neutrons. Electrons move around the nucleus in clouds, or shells, far from the nucleus.• When an atom is in balance, it has

the same number of protons and electrons. It can have a different number of neutrons.

PROTONS AND ELECTRONS ATTRACT EACH OTHER• Electrons stay in their shells because a special force

holds them there. Protons and electrons are attracted to each other. We say protons have a positive charge (+) and the electrons have a negative charge (-). Opposite charges attract each other.

ELECTRICITY IS MOVING ELECTRONS• The electrons near the nucleus are held tight to the

atom. Sometimes, the ones farthest away are not. We can push some of these electrons out of their shells. We can move them. Moving electrons are called electricity.

STATIC ELECTRICITY• Normally, the negative charges balance the positive charges.

The electrons are loosely held in the outer regions of an atom, and can be easily removed and transferred to other objects. This is called static electricity.

• Static electricity can build up in an object when one object rubs against another.

• For example, when you rub a balloon with a cloth, some of the electrons are transferred to the cloth to the balloon.

• Electricity has been around forever. Lightning is electricity. It is electrons moving from one cloud to another or jumping to the ground.

• Have you ever felt a shock after walking across the carpet? A bunch of electrons jumped to you from another object.

• This kind of electricity is called static electricity. Electrons aren’t moving through a wire, they are jumping from one object to another.

• Like magnets, opposite charges attract and like charges repel. So if the charged balloon is brought near an uncharged balloon, they will attract each other.

ELECTRONS REPEL EACH OTHER• Have you ever rubbed a balloon over your head.

Did your hair stand straight up on your head?• If so, you rubbed electrons off the balloon. The

electrons moved into your hair from the balloon. They tried to get far away from each other. They moved to the ends of your hair. They pushed against each other and made your hair move— they repelled each other.

Static Electricity

• Each of you will get a balloon, please inflate the balloon and tie it closed.– What do you think will happen if you rub the balloon on your

hair?– What will happen to the balloon?– What will happen to your hair if you place the balloon close

to your head?

TEST YOUR PREDICTIONS, Rub your balloons on your hair and then move the balloon a few centimetres away from your heads.

Why do you think your hair was attracted to the balloon?

• This is an example of static electricity.

• Insert diagram

• All objects have small particles of positive and negative charges. When two objects rub together, such as hair and a balloon, some of the negative charges from the hair are transferred to the balloon.

• This gives the balloon a negative charge, and the hair a positive charge. The hair and the balloon are attracted to each other because one has a positive charge and the other has a negative charge—similar to how opposite poles on a magnet attract each other.

Rub the balloons with a damp cloth. The water in the cloth picks up some of the electrons and balances the charges on the balloon, making it uncharged again. So the damp cloth neutralizes the balloon’s charge.

• Do you think a charged balloon would be attracted to something with no charge at all?

• Have you ever seen someone stick a balloon on the wall?• How was it done?• Do you think your balloon will stick to the wall if you do not

first rub the balloon against your hair or clothing?

Try sticking your balloon to the wall—without charging them (rubbing them on your hair/clothes).• Why didn’t your balloon stick?• What is needed in order for them to stick?

Rub the balloon on your hair/clothes. Now try to stick them to the wall.• Why did your balloon stick to the wall this time?• What charge did the balloon have?• Was anything rubbed against the wall?• Was the wall charged or uncharged?

Objects with a negative charge are attracted to both positively charged and uncharged objects. Also, objects with a positive charge are attracted to both negatively charged and uncharged objects.

Working Groups

• Each group should have: tissue paper, salt, pepper, and sheets of writing paper, as well as the Activity Sheet.

In Summary…

• Negatively and positively charged materials attract each other.

• Uncharged materials are attracted to charged materials.

• Materials of like charges repel each other.

Construct a Model of Static Electricity

• In your groups construct a model of static electricity.

• Use a paper plate to represent the balloon.• Use a sheet of paper to represent hair/clothes

that the balloon was rubbed against.• With plasticine, roll several balls to represent the

charges in the balloon and hair/clothing.• Red for positive charges and nucleus, blue for the

negative charges (electrons).

What happens when the balloon is rubbed on the hair or clothing?

-Show how the transfer of electrons from the hair/clothes to the balloon.

What charge does the balloon have now?What charge does the hair (or clothes) have now?What will occur because of these changes?

Current Electricity

The movement of electricity from one place to another is called current electricity. A current of electricity is created by a stream of moving electrons.

Where does electricity come from? How does this projector work? How did the electricity get from the wall to the projector?

• Why do you think it is called current electricity?

• What does the word current mean?• How does electrical energy travel?• How is current electricity different from static

electricity?

Quick Brainstorm

• Create a quick list of electrical devices used in home, school, and the community.

Electrical Devices Energy Transformation

LAMP Light energy

STOVE Heat energy

STEREO Sound energy

FAN Mechanical energy (movement)

Safety with Current Electricity• What are some of the dangers involved in using

current electricity?

• Good Safety Practices:– Use grounded plugs– Check cords for open and frayed wires– Use proper wattage of light bulbs in lamps– Never use electrical devices near water– Never insert anything but a plug into an outlet– Never plug more devices into an outlet than it can

accommodate.

Safety Posters

• With a partner, create a poster about electrical safety that can be put up around the school.

Homework: Sheet A/B

• A: Select a device that use current electricity. Draw a diagram of that device. Explain how current electricity is transformed into another form of energy. Describe how to use it safely.

• B: Identify several electrical devices and list them in the first column. Identify how the energy is transformed.

Electricity from Chemical Sources

MAGNETS ARE SPECIALIn most objects, all the atoms are in balance. Half of the electrons spin in one direction; half spin in the other direction. Magnets are different. In magnets, the atoms at one end have electrons spinning in one direction. The electrons at the other end spin in the opposite direction.The electrons don’t move from one end to the other to find a balance. They stay where they are, even though they’re out of balance. We call one end of the magnet the North (N) pole and the other end the South (S) pole. The force of the magnetic field flows from the North pole to the South pole.

• Have you ever held two magnets close to each other? They don’t act like most objects. If you try to push the two North poles (N) together, they repel each other. If you try to push the two South poles (S) together, they repel each other.

• Turn one magnet around and the North (N) and the South (S) poles attract. The magnets stick to each other with a strong force. Just like protons and electrons, opposites attract.