Question

The glowing of the bulb is based on effect……………….of electric current
a) heating
b) magnetic
c) luminous
d) none of the above

Answer 1

Hint: A bulb is basically analogous to a resistance connected across a source. When current passes through a resistor it generates heat during the duration of the current flowing through it. When a resistor is basically heated to a very high temperature it starts turning red and emits light. From this we can easily conclude that the bulb glows.

Complete step by step answer:
A bulb consists of a filament made of tungsten metal. When current is passed through the bulb the filament starts glowing and emits light. If the current drawn from the source is not sufficient enough the bulb does not glow. The heat produced in the bulb is given by $H=VIt....(1)$ where V is the potential difference developed across the bulb and t is the time for which current is passed through the bulb. Clearly, we can see from equation 1 that the bulb did not glow when the current was not sufficient enough, this is because heat generated was not sufficient to turn the filament of the bulb hot red. The filament is at its maximum glow when the metal of the filament is not oxidized. Hence bulbs are filled with non reactive gases.
Hence from the above conclusions drawn we can state that the bulb glows due to the heating effect of electric current. Hence the correct answer is option a.

Note:
It is to be noted that all the bulbs work on the heating effect of electric current. The CFL bulbs we use at our homes emit light due to the electron beam heating its white surface to produce light. The zero bulbs which have filament, are usually made of tungsten metal since it has a high melting point.