Question

Consider the following statements.
An ordinary light bulb has a rather short life because the
$1$. Filament wire is not uniform.
$2$. Bulb cannot be evacuated completely.
$3$. Wires supporting the filament melt at high temperatures.
Which of the given statements are correct?

• A. $1$ and $2$
• B. $2$ and $3$
• C. $1$ and $3$
• D. $1,2$ and $3$

Answer 1

The correct option is D $1,2$ and $3$

The electric light bulb uses a glowing wire filament heated by electrical resistance to white to generate light (a process known as thermal radiation). The 'bulb' is the glass enclosure which keeps the filament in a vacuum or low-pressure noble gas. Complete evacuation of bulb is not possible. A small quantity of gases left behind which expands on heating by heat through filament. Moreover, the wires supporting the filament sometimes melt due to high heat generated as a result of high resistance of filament. Thus, these factors leads to short life span of ordinary bulb.

Option D