Energy conversion pathway of an incandescent light bulb?

• A. Electrical energy → Thermal energy → Light energy
• B. Electrical energy → Light energy directly
• C. Electrical energy → Sound energy → Light energy
• D. Electrical energy → Chemical energy → Light energy

Answer: (A)

Incandescent bulbs generate light mainly by heating a filament until it radiates. The electrical energy that flows through the filament is converted into thermal energy due to the filament’s resistance. As the filament gets extremely hot, it emits electromagnetic radiation across a broad spectrum, including visible light. So the energy pathway is electrical energy → thermal energy → light energy. A lot of the energy also leaves as infrared heat, which is why these bulbs are not very energy-efficient. The other options don’t fit because the bulb’s light comes from heat produced by resistance, not directly from electrical energy, sound energy, or chemical energy.