The chemical energy stored in the chemicals stored inside a cell converts into electrical energy. When the chemicals of the cell are used up, it stops producing electricity.

The cells used in calculators are known as button cells, as they resemble the shape of a button. The plates of these cells are made from compounds of nickel and cadmium. The main advantage of these cells is that they can stay in an active stage for months without any leakage.

When two or more than two electric cells are connected together in such a way that the positive terminal of one cell is connected to the negative terminal of the other, then we call it a battery. A simple connection showing the combination of two electric cells to form a battery is shown below:

Current flows in our house appliances through the main switch. When it is turned off, flow of current stops and our lights and fans go off.

The cell will be used up rapidly in A because all the current will discharge through the wire very rapidly as any appliance is not connected between the positive and negative terminals.

The cell consists of a carbon rod present of the centre of the zinc container. By the side, metal cup present is positive terminal and opposite to that is a metal disc which is of negative terminal.

A rechargeable battery has such chemicals which on after use can be restored by passing suitable current in the opposite direction to the rechargeable batteries, so it can be used again and again.

A device which is used to close or open a circuit is known as-switch, so when we open the switch, there exists an air gap which does not allow the current to pass through it. On the other hand, when it is closed, then there is not any existence of air gap between the wires and therefore in this way, it conducts electricity.

(a) Vimlesh is intelligent and has good knowledge of current and its hazard.
(b) A plastic glove is an insulator. It does not conduct electricity.

Among copper, silver and aluminium, we use copper and aluminium not silver for household wires because copper and aluminium are much cheaper than silver and silver is used as an ornaments and is also heavier than copper and aluminium.

As we know that human body is a good conductor of electricity. So, it is necessary to prevent it from electric shocks.
On the other hand, plastic and rubber are insulators that do not allow electricity to pass through them. Hence, electricians use screwdrivers and pliers which have plastic or rubber covering on them for repair the work.

An electrician should use rubber gloves while repairing an electric switch because rubber is an insulator that does not allow electric current to pass through it. Thus, it prevents his body to get electric shocks.
On the other hand, human body is a conductor of electricity, so it is necessary to prevent it from electric shocks.

Since, eraser is an insulator that means itis a bad conductor of electricity. So, conduction of electric current is not possible. Thus, if instead of safety pin, an eraser is used, bulb will not glow.

Switch is a simple device that is used to either break the electric circuit or to complete it. With the help of a switch, we can use an appliance according to our desire.
The switches used in lighting of electric bulbs and other devices in home works on the same principle.
Some electrical gadgets that are switches built into them are as follows:
(i) Torch
(ii) Table fan
(iii) Television set
(iv) Radio
(v) Electric iron

Here, the two phenomena we must check. One is the usage of conductors and the other is insulators which can stop the flow of electric current. We observe that the one end of screw driver is made up of metal and the other is made up of an insulator. Thus, electric current starts through one end but stops at the other end and hence, current cannot flow through it. Thus, bulb will not glow.