Question

Explain the following.
(a) Why is the tungsten used almost exclusively for filament of electric lamps?
(b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
(c) Why is the series arrangement not used for domestic circuits?
(d) How does the resistance of a wire vary with its area of cross-section?
(e) Why are copper and aluminium wires usually employed for electricity transmission?

Answer 1

Answer:

when the tungsten is heated up it produces light and that is why it is almost exclusively for filament of electric lamps.Conductor of electric heating devices such as toaster or electric iron is made of an alloy rather than pure metal because if electric heating devices are made up of pure metal then the metal melt easily when heat is increase and pure metal get corrode easily. In series circuits, all electrical switches will have common switch due to which they cannot be turned off/On separately. appliances . ---> Overall resistance of circuit will increase due to which the current from power supply will be less. Hence we prefer Parallel Circuits for domestic wiring.Resistance is inversely related to cross-sectional area. The larger cross-sectional area means less wire resistance. ... It is inversely proportional to the area of cross section of the wire. The more the area of cross section of the wire,the less is the resistance and the less the area,the more is the resistance.Copper and aluminium wires are generally used for electricity transmission as they have low resistivity. Low resistivity decreases the resistance and hence increases the amount of current in the circuit. Therefore, they are good conductors of electricity.

Explanation: