# Electricity – circuits, static electricity & powering a clock with potato!

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In fourth class we have been learning about electricity. We have been making circuits and static electricity.

Electricity is a flow of tiny particles called electrons which can travel through wires. This flow is often called an electric current.
An electric circuit is a closed loop path traveled by electricity from a source of power.
An open circuit is where there is a break in the path which stops the electricity from flowing through.

How to Make a Circuit

Step 1: Put the batteries into the battery holder making sure they are the right way around
Step 2: Place one wire to the end of the bulb, and the other wire to the other end.

This formed a circuit and lit up the bulb

Why do we need wires?

We need wires so that the electrical current can flow in a loop between the battery and the light and between the light and the battery.

Batteries
Batteries use energy stored in chemicals to allow electric current to flow. Once this is store is used up, current can no longer flow. We need the batteries to provide the right conditions for electricity to flow through the circuit. The battery gives the light the energy it needs.

Play the BBC Bitewise Circuit Game here.

Static Electricity
Have you ever gotten a little shock when you open a car door? This is static electricity.

### Opposites Attract

Now, positive and negative charges behave in interesting ways. Did you ever hear the saying that opposites attract? Well, it’s true. Two things with opposite, or different charges (a positive and a negative) will attract, or pull towards each other. Things with the same charge (two positives or two negatives) will repel, or push away from each other.

A charged object will also attract something that is neutral. Think about how you can make a balloon stick to the wall.

If you charge a balloon by rubbing it on your hair, it picks up extra electrons and has a negative charge. Holding it near a neutral object will make the charges in that object move.

• If it is a conductor, many electrons move easily to the other side, as far from the balloon as possible.
• If it is an insulator, the electrons in the atoms and molecules can only move very slightly to one side, away from the balloon.
• In either case, there are more positive charges closer to the negative balloon.
• Opposites attract. The balloon sticks. (At least until the electrons on the balloon slowly leak off.) It works the same way for neutral and positively charged objects.
• So what does all this have to do with static shocks? Or static electricity in hair?
• When you take off your wool hat, it rubs against your hair. Electrons move from your hair to the hat. A static charge builds up and now each of the hairs has the same positive charge.
• Remember, things with the same charge repel each other. So the hairs try to get as far from each other as possible. The farthest they can get is by standing up and away from the others. And that is how static electricity causes a bad hair day!
• It happens because electrons build up in our body and then flow to a metal object. Click on the balloons to read all about it.
• Fun facts about static electricity
• A spark of static electricity can measure thousands of volts, but has very little current and lasts for a short period of time. This means it has little power or energy.
• Lighting is a powerful and dangerous example of static electricity.
• As dangerous as lighting is, around 70% of people struck by lightning survive.
• Temperatures in a lightning bolt can hit 50,000 degrees F.
• Static electricity will be worse on a dry non-humid day.
• How To Make Static Electricity
• Method:
Step 1: Measure a piece of thread 12 inches in length and tie a piece of cereal to one end of it. Find a place to attach the other end so that the cereal does not hang close to anything else.
Step 2: Charge the balloon by rubbing it vigorously on a wool sweater.
Step 3: Slowly bring the balloon near the cereal. It will swing to touch the balloon. Hold it still until the cereal jumps away by itself.
Step 4: Now try to touch the balloon to the cereal again. It will move away as the balloon approaches.
• Potato Clock
In Fourth Class we also powered a digital clock using potatoes. We had a lot of fun doing this.