Question

give reason why (i)tungsten is used for making filament of electric lamps; (ii) the elements of heating electrical appliaces are made up of an alloy rather than pure metal

Answer 1

Tungsten is used because it do not flow in the bulb and make it to glow.

Answer 2

(i) Tungsten wire is used for making filament of electric lamps because -
(a) it has a very high melting point.
(b) when current passes through it, it becomes 'white - hot' and glows brightly for a long time.
(c) it is quite stable and has a long life 'burn out' or possible oxidation.
(d) when electric current flows through the metal filament of the bulb it gets heated to a very high temperature.



(ii) The elements of heating electric appliances are made up of an alloy rather than pure metal because -
(a) it has a high melting point.
(b) it has a high resistivity.
(c) it can remain red 'red - hot' for a long time without getting oxidised or 'burning out'.
(d) when any such appliance is switched on, a large amount of heat is produced in its heating coil.







Hope it helps you.
With regards@
Tanisha