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?

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Solution

(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.

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Similar questions

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?

(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?

Tungsten do not oxidize at high temperature. Can it be the reason for tungsten used almost exclusively for filament of electric lamps?

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