ABOUT ELECTRICITY

In everyday life we find bulbs in lampshades or fluorescent tubes all around us in houses, offices, restaurants etc. You must have wondered what causes the bulb or the tube to light up ? " Actually they need the electricity to light up. Electricity passes through wires that are attached to them and it makes the bulbs and tubes glow.

All things are made up of very thin particles called atoms. Everything from metals, wood, glass, water and gases are made of atoms.

We cannot see atoms because they are very, very small. However, scientists have found out that even atoms are made up of smaller particles. One of the many types of particles in an atom is the electron.

We get electric current because of the movement of the electrons. So, current is the flow of electrons. One might imagine electrons traveling from one end of the wire to the other end and making a continuous flow, just like the flow of water in a pipe ( though the two are not exactly identical ).

Electricity travels along a path. If the path is blocked, then electricity cannot keep flowing. The whole path along which electricity travels is known as a circuit. A broken path is known as an 'Open Circuit' and the electricity can not flow in an open circuit. An unbroken path is known as a 'Closed Circuit' and the electricity can flow.

Some materials allow electricity to flow through them easily, some materials do not. The materials that allow electricity to flow through them easily are known as conductors. The materials through which it is difficult for electricity to flow are known as insulators or non- conductors. Conductors are useful to us because they allow electricity to flow through them.

However, sometimes we do not want electricity to flow, in certain instances. And so we have to use insulators to prevent the flow of electricity. For example we use rubber or plastic insulators to cover electric wires in order to prevent electricity form flowing into our body. Otherwise we will get an electric shock. So insulators are also useful to us.

We use electricity very often. We use electricity to work our radios, to run our fans, in electric kettles to boil water and also to get light from the bulb.

However, we do not keep our radio 'on' all the time. And if it is cold, we do not want the fan to keep running. After the water has boiled, we do not need electricity any more. We definitely do not need to have the light 'on' when it is very bright. Therefore we must have a way and a device to turn electricity 'on' and 'off', whenever we need to.

We use a switch to turn electricity 'on' and 'off'. The function of the switch is mainly to 'make' or 'break' the circuit, thereby sometimes allowing the electricity to travel (ON POSITION) and otherwise making the flow of electricity stop (OFF POSITION) .

There are mainly two kinds of batteries namely primary and secondary. The primary batteries we use are known as dry cells. Many other types of dry cells are shown in the picture. A dry cell can give a steady current for a certain time after which the current becomes weaker and weaker and finally it produces no more current. It is of no use to us anymore. This is one type of battery.

On the other hand, the secondary battery is known as wet cell. We call it a wet cell because inside the cell there is liquid. We also call the wet cell shown below 'an accumulator'. It can give us electricity for a longer time. And when it becomes weak it starts giving lesser current, we recharge it. After recharging the wet cell becomes as good as new and starts giving normal current again.

The electricity, which we use for electric bulbs, fans, kettles and irons, is produced by 'generators'. A generator is actually a very big dynamo. It can produce a very large amount of electricity. Number of generators produce power in Power Station. Electricity produced at a power station is allowed to flow through metallic cables, which run from the Power Station to our houses and offices. Then they run back from our houses and offices to the power station, forming a closed circuit ( remember the essential condition for the flow of current - the closed circuit ! ). Don't be surprised if you don't see many cables running from pole to pole, they can be laid underground too !

Our common experience is that whenever we put our hand near a lighted electric bulb, we feel the heat coming from the bulb. Similarly, we can feel a touch of heat from a lighted torch after sometime. Also if we switch on an electric kettle containing water the water starts boiling after sometime. Actually there is a long piece of coiled wire inside the kettle, when electricity passes through it, heat is produced which makes the water boil.

We notice that every time electricity is passed through the thin wire of a bulb, light is produced. We say that some of the electricity has been 'changed' to light. Actually, the changing of electricity into heat takes place first. The electricity that passes through the thin tungsten wire inside the bulb, makes the wire very hot. The wire becomes so hot that is glows. When it glows, it gives off light. Similarly electricity is converted to light in a fluorescent lamp too.

But whereas a tungsten bulb uses up a lot of electricity before light is produced, a fluorescent lamp uses up only a small amount of electricity to produce light. Therefore for the same amount of electricity a fluorescent lamp gives off more light than a tungsten bulb.

Electricity can be converted into heat, light or magnetism. In fact electricity, heat, light and magnetism are all forms of energy. There are many more forms of energy. And they can be converted into one another. For example electrical energy can be changed to light energy, heat energy or magnetic energy.

Electricity is very useful to us in many ways. We can use to make our lives more comfortable. But it can be very DANGEROUS to us too. Here are a few tips to stay away from harm

Do not touch a bare wire from the main electrical circuit. It may be a live wire i.e. electricity might be traveling through it. If you touch it, the electricity will flow into your body and might give you an electric shock.
Climbing a lamppost carrying electric wires is dangerous. A lamppost is usually made of metal and is therefore a good conductor of electricity. Some electricity may escape from the electric wires to the lamppost and so you could be electrocuted.
Do not push a needle through an electric wire. An electric wire is covered by rubber or plastic insulators. If you do so, electric current will flow through the needle to your body and give you a shock .
Do not try to repair electrical appliances. Leave it to an electrician.
Touching an electrical appliance with wet hands is dangerous ! Water can conduct electricity.

Ask an electrician to educate you about electrical safety.

-     Electric current in a wire is something like water current in a pipe.

-    The amount of electricity passing through the wire per second is measured in ampere (A).

-   The "pressure" pushing the electricity along the wire is measured in Volt (V). For example a torch battery is 1½ Volts,   a   car battery is 6 Volts or 12 Volts. Electricity running in the cables in your house is 240 volts.

- The amount of electrical energy used in homes, offices, etc. is measured by an electricity meter in kilowatt-hours.

- Watt is the unit of power or rate of doing work. A kilowatt-hour is the electrical energy supplied at a rate of 1,000 watts for 1 hour.