Which of the following metals is used as filament in lighting bulbs?

Explanation

Generally, the resistivity of alloys is higher than that of the pure metals from which they are made. Also, the rate of change of resistivity with change in temperature is comparatively low. Therefore, they do not oxidize quickly at high temperatures. For this reason, they are used in common electrical heating devices like electric presses, toasters, etc. For making filaments of incandescent lamps, only tungsten is used, whereas copper and aluminium are used to make wires for electric transmission. (366) ## Page 15 ## Conductivity