Electricity

Thinking back… atoms protons electrons + - All matter is made up of ______________. The two types of sub-atomic particles that have a charge are _______________ and ______________. Protons - _____ charge Electrons - _____ charge atoms protons protons electrons + electrons -

Electricity comes from the movement or placement of these charged particles.

Think about a magnet… What happens when you try to touch the two north ends together? They repel each other What happens when you try to touch the two south ends together? What happens when you try to touch the north and south ends together? They attract each other

Mini-Lab Number your group members 1-4. Student 1: Blow up and tie off a balloon. Then tie a string around the balloon’s knot. Student 2: Blow up another balloon and tie it off. Student 3: Hold the end of the string allowing the balloon to dangle. Student 4: Rub the balloon without the string on your hair. (This gives the balloon a negative charge – electrons move from your hair to the balloon) Student 1: Rub the balloon with the string on your hair. Student 4: Slowly move your balloon toward the hanging balloon. What happens? Student 2: Rub the hanging balloon with a dryer sheet. What does this do to the balloon’s charge? Mini-Lab

The same applies to ELECTRIC CHARGES Charges that are the same, repel each other. Charges that are different, attract each other. Two Protons Two Electrons Proton & Electron

What’s going to happen? + + - - + -

The charges of protons and electrons cause the object they make up to be positively or negatively charged. + + - - - + + - - + - - + + + - + + + + - - + - + + + - - + - +

Most objects normally have no overall charge. This is because each atom has an equal number of protons and electrons.

How can we tell if an object has a charge? Watch how it reacts with other objects. Use an Electroscope. Tomorrow, we will build an electroscope and test various objects.

Sometimes, the attraction between protons and electrons can cause an electron to move from one atom to another.

So an object can become charged by gaining or losing electrons. When an object loses electrons, it will have a _____________ charge. When an object gains electrons, it will have a _____________ charge. - + + - - - positive + + - + - + - + negative - + - -

Charge It! See how many balloons you can stick to one member of your group in 2 minutes. The balloons must be stuck to the student for them to count.

That’s Static Electricity! The build-up of electric charges Static means “not moving” or “not changing” In static electricity, charges build up on an object, but they do not flow continuously.

How can an object become charged? Three ways to move electrons from one object to another: Friction - rubbing Conduction - touch Induction – movement of electrons within an object

Often, a static discharge produces a spark. When a negatively charged object and a positively charged object are brought together, electrons transfer until both objects have the same charge. Static discharge is the loss of static electricity as electric charges transfer from one object to another.

Lightning is another example of static discharge.