Question

what is a major drawback of conventional incandescent light bulbs in terms of efficiency? they dont produce enough heat. 95% of the energy is converted to heat. they are too bright

Explanation:

To determine the major drawback of incandescent bulbs in efficiency, we analyze each option:

• "They don't produce enough heat" is incorrect because incandescent bulbs produce significant heat, and lack of heat isn't an efficiency drawback.
• "95% of the energy is converted to heat" is correct. Incandescent bulbs work by heating a filament; most energy (≈95%) becomes heat, not light, making them inefficient for lighting.
• "They are too bright" is incorrect as brightness isn't an efficiency - related drawback (efficiency is about energy conversion to useful output, here light).

Answer:

95% of the energy is converted to heat.