Why should switches always be connected to the live wire?

A switch must be connected in the :

Name two safety devices which are connected to the live wire of a household electric circuit.

Fig. below shows two bulbs with switches and fuse connected to the mains through a three pin socket by means of a three wires cable. Label each component - bulb, switch, fuse and socket.

Fig. below shows two bulbs with switches and fuse connected to the mains through a three pin socket by means of a three wires cable. Name and state the colour of insulation of each wire 1, 2 and 3.

Fig. below shows two bulbs with switches and fuse connected to the mains through a three pin socket by means of a three wires cable. How are the two bulbs joined : in series or in parallel ?

How should the several electric lamps be connected with the mains so that the switching on or off a lamp has no effect on the operation of other lamps ?

Will current flow more easily through a thick wire or a thin wire of the same material when connected to the same source ? Why ?

Will current flow more easily through a thick wire or a thin wire of the same material when connected to the same source ? Why ?

The diagram in Fig. shows the electrical system of a car to operate the two head lights and two rear lights by a switch. shows a connection to the body of the car. The two rear lights as connected in diagram glow faintly. Why do they glow faintly? How should they be connected to glow brightly ? Show by a separate diagram.

A power circuit uses a cable having three different wires. To which wire should the switch and fuse be connected ?