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 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 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.

An electric switch is a device used to complete or break an electric circuit. Usually, it is manually operated.
Purpose of using electric switch: In 'ON' position, the switch allows the current to flow through the circuit. Thus, the circuit becomes a closed circuit. In 'OFF' position, the switch does not allow current to flow through the circuit. Thus, the circuit becomes an open circuit.
Examples: Electrical appliances such as fans, electric lamps, washing machines, juicer and mixer, TV radio, etc, have switches.

An electric cell consists of a cylindrical pot which is covered by a thick paper sheet.

It consists of two terminals. One is called positive terminal and the other is called negative terminal. The metal cap is the positive terminal and the metal disc is the negative terminal of the electric cell.
The production of electric current takes place due to the chemical reactions inside the cell. The chemicals are present between the outermost covering of the cell and carbon rod.

This can be done by arranging the circuit as the given diagram.
One terminal should be connected to the terminal of the cell directly and other terminal can be connected using the given wire.

Current can only flow through a body if it gets the way to pass through it. In case of the earth, it gets the way from base wire to your body to the earth. In case of plastic chair or dry wood chair, it doesn't get the way to flow. So, you don't get any electric shock.

The arrangement of bulb should be such that positive terminal of a battery touches the base of the bulb. When switch ON, bulb will glow.

(a) The direction of current will be from Q to P in A and direction of current will be from P to Q in B. Because direction of current is always from positive terminal to negative terminal of the cell or battery.
(b) Yes, the bulb will glow in both the cases because to glow the bulb, we just need to complete the circuit.
(c) No, the brightness of the bulb never depend upon the direction of current passing through it.