Question

When the current passes through the filament, it gets heated to incandescence and give light while the connecting wires are not heated because

• A. the connecting wires are good conductor of heat while the filament is bad conductor.
• B. the connecting wires are of low resistance while the filament is of high resistance.
• C. the density of connecting wires is less than that of the filament.
• D. the connecting wires are bad conductor of heat while the filament is good conductor.

Answer 1

Answer: (A), (B)

the connecting wires are good conductor of heat while the filament is bad conductor.
the connecting wires are of low resistance while the filament is of high resistance.

The connecting wires are usually made of conductors such as copper and aluminium which have negligible resistance.In contrast, filament is made of material with high resistance.
We can see from joule's law that $P=i^{2}R⟹P\propto R$ .
Therefore, bulb filament gets heated and lighted up whereas the connecting wire does not.