In which of the following, heat loss is primarily NOT due to convection?

Correct answer: Heating of glass surface of a bulb due to current in filament

Explanation: ✅ Correct Answer: D) Heating of glass surface of a bulb due to current in filament 📚 Explanation: Convection requires the actual physical movement of fluid molecules (liquids or gases) to transfer heat, as seen in boiling water or sea breezes. The heating of a light bulb's glass surface by its filament happens through radiation and conduction across the internal vacuum or gas gap. Therefore, option D is the correct exception where convection is not the primary mode of heat transfer. Radiation allows heat energy to travel across space without relying on fluid currents.