Explain the following:
​(a) Why is tungsten used almost exclusively for filament of electric lamps?
(b) Why are copper and aluminium wires usually used for electricity transmission?
​(c)Why is nichrome alloy used for making elements of electric irons?

(a) Tungsten is used for the filament of electric lamps because it has a very high melting point, so it does not melt when the electricity is passed through it. That's why the temperature of the wire can be increased to a high value without melting the wire. Higher the temperature of the filament whiter the light.

(b) Copper and aluminium wires are the good conductors of electricity, as they have a very low resistivity. Low resistivity decreases the resistance of transmission wires and hence increases the amount of current flow in the circuit.

(c) The nichrome wire is used for making the elements of electric irons because it has a very high resistivity along with a very high melting point, which makes it perfect as a heating element of the electric appliances.