1. Introduction to Static Electricity
What is static Electricity?
The word electricity comes from the Greek word Electron pronounced electron.
This was their word for a material, which we call amber today.
The Greeks had discovered that, if amber was rubbed with a cloth, it would attract dust and light materials to it.
You have probably met many modern-day materials, which will do the same thing. Plastics are often good at this.
When a material can behave like amber does, we say that it gets an electric charge when it is rubbed. Sometimes we say that we are charging up the material.
Sometimes people call it static or even static electricity.
Notes: Copy and complete the sentences below.
When a material behaves like amber after being rubbed, we say that is has got an ______.
This kind of electricity is often called ______.
Notes: In static electricity we use three important
words, attract, repel and static.
To help us understand what they mean copy and
complete the three sentences below using the
words attract, repel and static.
Bees visit many flowers each day. The smell and colour of the flower ______the bees to
them.
In summer midges are a pest. We often use
special creams to ______them.
Shop windows often have displays of dummies. Since they do not move we call this a
______display.
Collect: Perspex rod
Piece of paper
Balloon
Paper towel
Activity: Activity 1
a. Tear up the piece of paper into small bits.
b. Rub the Perspex rod with the paper towel,
this charges up the rod with static
electricity.
c. Bring the charged end of the rod near to, but
not touching, the small bits of paper. Look at
what happens.
Activity 2
a. Turn on a tap of water to give a thin stream
of water.
b. Charge up the Perspex rod with the paper
towel again and bring it near to, but not
touching, the stream of water. Look at what
happens.
Activity 3
a. Blow up the balloon and tie the end so no air
can escape.
b. Rub the balloon with the paper towel. You
should now be able to stick the balloon to the
wall with the charged side.
Notes: Write a sentence to describe what happened in
each activity.
Discussion: In your group discuss the reasons why the small
bits of paper, the thin stream of water and the
balloon act the way they do.
2. Different types of charge
Collect: 4 Plastic rods of different materials
2 watch glasses
2 paper towels
Rod in handPolythene(P) / Nylon(N) / Ebonite(E) / Acetate(A)
Rod on glass / Polythene(P)
Nylon(N)
Ebonite(E)
Acetate(A)
Notes: Copy the following table.
Activity:
1. Place the two watch glasses back to back as
shown in the diagram below to make a
turntable. The top watch glass should be able
to spin easily on the bottom one.
2. Take any rod and hold it by the labelled end.
Rub the other end with a paper towel to
charge it. This should only take two or three
firm rubs. Place the rod carefully on the
upper watch glass, so that the rod is
balanced. Take care not to touch anything
with the charged end of the rod. If you do
touch anything with the charge end, rub it
again to charge it up.
3. Take another rod hold it with the labelled end
and rub the other end with the other paper
towel to charge it.
4. Bring the charged end of this rod near to the
side of the charged end of the rod on the
watch glass. Take care that the two rods do
not touch each other.
5. Look at what happens to the rod on the watch
glass. Something should always happen, if it
does not then start again. If you still cannot
get anything to happen ask your teacher for
help.
6. Fill in the correct space in your table with the
result of this experiment. Use the words
attract or repel to describe what happens.
7. Repeat this for all other pairs of rods in your
table. For two rods of the same material you
will have to borrow the extra rod from the
group next to you, remember to ask them
before you take the rod.
Notes: Copy the diagram of the apparatus.
Copy the following table into your jotter.
Materials which repel polythene / Materials which repel NylonActivity: Use the results from the experiment to complete
the table.
Notice that no material appears in both columns.
What have we learned from this experiment?
These results show us that there are only two
types of electrical charge.
We do not have enough time to try all other
possible materials, but Scientists have never
found a material which does not fit into one of
these groups.
Scientists decided to call these two different
charges positive and negative.
Polythene and materials, which repel polythene
have a negative charge.
Nylon and materials which repel Nylon have a
positive charge.
Notes: Copy and complete the following sentences. Use
the information above and from your experiment
to help you.
The results of our experiment show us that there
are only ______types of electrical charge.
One type of electrical charge is called
______, and the other is called
______.
When a positive charge is brought near another
positive charge they ______each other.
When a negative charge is brought near to
another negative charge they ______each
other.
When a positive charge is brought near to a
negative charge they ______each other.
3. Van de Graaf Generator
Activity: Your teacher will show you a machine called the
Van de Graaf Generator. This can produce lots of
static electricity. It is basically a very simple
machine and a lot of fun can be had with it, but
try to listen to what is said and explain what you
have seen afterwards.
Notes: Answer the following questions in sentences
about what you saw with the Van de Graaf
Generator.
1. What did you see happening when the small
metal ball was brought near to the dome of
the Van de Graaf Generator?
2. What caused this to happen?
3. What happened to the sphere when it was brought up to and touched the Van de Graaf Generator dome?
4. Explain why this happened.
5. What happened to the pupil’s hair when
she/he touched the top of the Van de Graaf
Generator while they were standing on the
polystyrene block?
6. Explain why this happened.
Current Electricity
So far we have looked at what we call static
electricity, that is electricity that is standing
still.
We are now going to look at electricity on the
move, this moving electricity is called an
electrical current.
Notes: Copy the heading ‘current electricity’
Activity: Your teacher will show you an ammeter. This
meter is used to show when electrical charge is
moving. The symbol we use for an ammeter in
diagrams is
The ammeter is connected with the Van de Graaf
Generator as shown below.
Notes: Copy the above diagram.
Answer the following questions in sentences.
1. When did the pointer on the ammeter move?
2. What is passing from the dome to the metal ball?
4. Current electricity
Although the Van de Graaf Generator can be used to make an electrical current, the current it produces is very small. For many of our uses of electricity we need a much bigger current.
Activity: Your teacher will now connect a cell to an
Ammeter.
Notes: Copy the above diagram.
Answer the following questions in sentences.
1. When did the pointer on the ammeter move?
2. What is flowing from the cell to make the ammeter give a reading?
Warning
Although we get most of our electricity from the mains supply, it is very dangerous to experiment with this.
NEVER EXPERIMENT WITH MAINS ELECTRICITY
In our experiments in electricity we will use a safe supply. This is called a cell. Most cells use chemicals to make electricity.
We usually do not see the chemicals, only the metal connections or terminals.
One of the terminals is marked + for positive the other is marked – for negative.
When a cell is being used to give an electrical current, negative charges in the wire are repelled from the negative terminal and are attracted to the positive terminal.
An electrical current is a flow of negative charges.
Notes: Copy the diagram below, and copy and complete
the sentences.
An electrical current is a flow of ______
charges.
The safe supply of electricity we use in school is
called a ______.
Most cells use ______to make electricity.
The negative end of a cell ______the
negative charges in the wire, and the positive end
______the negative charges.
Electrical circuits
Collect: Bulb, cell, two leads.
Activity:
Using the apparatus you have collected make
the bulb light. That is make the filament glow.
Notes: Draw a diagram of the apparatus when the bulb
filament is glowing.
Copy and complete the sentence below.
To make the bulb light up, that is make the
filament glow, the ______of the bulb has
to be connected to one end of a cell and the
______to the other end of the cell.
Collect: A bulb in a holder, cell in a holder, two leads.
To make connecting bulbs and cells easier, we use special holders. If you look carefully you will see that the metal terminals of the holders are connected to the same parts of the bulb and cell as in you experiment.
Activity: Connect the cell to the bulb with the leads, so
that the bulb lights.
Electrical diagrams
Diagrams of experiments in electricity are often very complicated to draw, so we use special symbols to stand for different parts.
Here are some we use most often.
Notes: Copy the above diagrams, with their labels.
5. A complete circuit
Collect Bulb in holder, cell in holder, two leads.
Activity Set up the following arrangements of the
apparatus. Some will make the bulb light, others
will not.
In groups discuss the following questions.
1. In which arrangement did the bulb light?
2. What was important about the circuit which allowed the bulb to light?
3. What must be moving in the wires to make the bulb light?
Notes: Copy the information below.
For an electrical current to flow there must be a
complete circuit. That is a complete path from
the negative terminal to the positive terminal of
a cell, for negative charges to flow.
Conductors and insulators
In the last activity the bulb was connected to the cell using wires made of copper. Does the material the connector is made from have any effect on the flow of negative charges? The following activity will help answer this question.
Collect: Bulb, cell, 3 leads, 2 crocodile clips, set of
materials.
Notes: Copy the above title then the following table and
circuit.
Material / Bulb on or off / Conductor or insulatorAir / off / insulator
Activity: 1. Set up the above circuit.
2. Connect each material in turn between the
crocodile clips to complete the circuit.
3. Note the name of the material in the table and
whether the bulb was on or off.
4. If the bulb lights the material is a conductor,
that is it will allow an electrical current to flow
through it. If the bulb does not light the
material is an insulator, that is it will not allow
an electrical current to flow through it. For
each material in your table fill in whether it is
a conductor or an insulator.
Notes: Copy and complete the information below.
For a current to flow the materials used to make
the circuit have to be ______.
Materials that are ______do not allow a
current to flow.
6. Series and parallel circuits
Series circuits
Collect: 2 cells, 3 bulbs, 5 leads
Activity: 1. Set up the following circuit, you will not use all
of the apparatus you have collected.
2. Take another bulb and ONE lead. Connect the
second bulb to the circuit using only the ONE
lead so that both bulbs are lit. You can
disconnect any part of the first circuit.
3. Unscrew one bulb and look at what happens to
the other bulb.
4. Add a third bulb to the circuit using one more
lead. Look at what happens to the brightness of
the bulbs. Again unscrew one bulb and look at
what happens to the other bulbs.
Notes: Copy the title above. Draw circuit diagrams of
the three circuits you have made.
Discussion: Discuss the following questions with your group.
1. In each circuit you made, how many different
paths are there for the negative charges to
flow from the negative terminal of the cell to
the positive terminal of the cell?
2. What happened to the brightness of the bulbs
when the second and third bulbs were added to
the circuit?
3. What happened to the other bulbs when you
unscrewed one bulb?
4. Explain your answer to question 3.
Copy the following information.
When bulbs are arranged in this way we say they
are arranged in series, and that the circuit is a
series circuit.
There is only one path for the charge to move
around a series circuit.
As more bulbs are added in series the dimmer
they get.
If there is a break in a series circuit the current