Experiments: Electricity

--Static Electricity--

Attractive Comb

You will need a plastic comb, a clean head of hair and a tiny piece of paper or tissue (about 12 centimetre in size).

Comb your hair vigorously, and then bring the comb close to but not touching the paper. Watch what happens.

This is a static electricity experiment and is best done on a very dry day. Electrons have been rubbed off one object onto the other. This leaves one object with a positive charge and the other object with a negative charge. Opposite or unlike-charged objects attract. You can repeat the experiment and bring the comb close to a fine stream of running water, and it will attract the water. You can also attract rice bubbles at the breakfast table while you get ready for school.

Repulsive Straws

You will need a clean head of hair and 2 drinking straws.

With a straw in each hand, rub the straws vigorously in your hair for a few minutes. Hold the straws lightly by their ends so that they are hanging close to each other but not touching. Watch them move.

The straws have the same electric charge so they will repel each other. Static electricity experiments like this are best done on a very dry day.

You can use balloons instead of straws, and a woollen jumper instead of your hair.

--Current Electricity--

Make a Lemon Battery

Safety Rules:
Parent supervision
Take care with electricity

Materials you need are:
a torch bulb
2 electrical wires (about 30 centimetres in length)
a lemon
2 long thin objects that are made of different metals or graphite that you
can poke into the lemon (e.g. a steel paperclip, a copper nail, a pencil sharpened at both ends)

Lemon Battery Diagram

Gently squeeze the whole lemon to make it juicier inside. Poke the two different metal or graphite electrodes into the lemon. Attach the wires to the electrodes and also to the light bulb to make a circuit. The light bulb should glow.

This is an electric cell that produces electricity. It is made from two electrodes of different types (i.e. different metals or graphite) and an electrolyte solution (the lemon juice). Try this using lemon juice in a jar instead or using a whole potato.

Make Electricity in your Mouth

Find a person who has the older darker mercury-containing tooth fillings. Ask them to put a piece of aluminium foil over the filling and bite down on it. They should feel a slight zap! (Do not do this to a person with a heart condition.)

When two different metals (electrodes) are placed in a salty solution such as saliva (electrolyte), they form a simple electric cell and will generate a small amount of electricity.

Series and Parallel Circuits

Safety rules:
Parent supervision
Take care with electricity

Materials you need are:
one torch battery
4 electrical wires
2 torch bulbs

Series Circuit Diagram

Wire up a series circuit with only one bulb. Then wire up a series circuit with two bulbs. What do you notice about the brightness of the bulbs?

Now wire up a parallel circuit with two bulbs. What do you notice?

The bulbs in the series circuit get dimmer, but when wired into the parallel circuit, they stay equally bright. Our homes and buildings are wired in parallel not in series.

Steadiness Tester

Safety rules:
Parent supervision
Take care with electricity
Take care with tools

Materials you need are:
a torch battery
a torch bulb
2 wire coat hangers
2 electrical wires
a base board
an electric drill or hammer and nail

Steadiness Tester Diagram

Make a small loop in one of the wire coat hangers. Make the second wire coat hanger an obstacle course by winding it in all sorts of directions. Set up the apparatus as in the diagram, making the second wire coat hanger obstacle course as sturdy as possible in to base board.

Now try to move the loop along the obstacle course without making contact.

If you make contact, you will be completing the circuit and the light bulb will glow.

Wiggling Light Bulb

You will need an incandescent light bulb and a magnet (e.g. a bar magnet or a strong refrigerator magnet).

Turn on the light bulb. Hold the magnet close to the glass bulb and watch the wire filament wiggle.

The AC (Alternating Current) has a frequency of 50 cycles per second, and this is how fast you are seeing the filament wiggle.