Question

When does an electric bulb have to be replaced?

Answer 1

• When an electric bulb glows a physical change is observed. As the light produced by the electric bulb is due to the heating effect of the conductor. Even though there is an occurrence of temperature change since no new substances are produced it is considered to be a physical change.

• When an electric bulb glows a physical change is observed. As the light produced by the electric bulb is due to the heating effect of the conductor. Even though there is an occurrence of temperature change since no new substances are produced it is considered to be a physical change.Hence, option A is correct.

Answer 2

Answer:

when its filament (made up of tunsten) is burnt or broken