Question

incandescent light bulbs are notorious for being relatively inefficient in producing visible light. the tungsten wire inside such a bulb is at a temperature of approximately 3000 k and the emission spectrum is very similar to that of a blackbody. the efficiency is so low because:

Answer 1

Incandescent light bulbs have low efficiency because much of the electricity is converted into heat, not visible light. The high temperature tungsten filament radiates energy as a blackbody, with most of it being infrared radiation. Additionally, tungsten evaporation contributes to inefficiency and bulb failure over time.

Step-by-step explanation:

The efficiency of incandescent light bulbs is so low primarily because a significant portion of the energy is converted into heat rather than visible light. The tungsten wire filament inside the bulb reaches temperatures of approximately 3000 K, emitting a spectrum similar to a blackbody. However, the nature of this thermal radiation means that much of the energy is not in the visible light range but rather in the infrared, which we perceive as heat. This is why incandescent bulbs are known to be relatively inefficient, and over time, they have been replaced by more energy-efficient options such as LED and CFL bulbs.

Another factor is that tungsten evaporates at high temperatures, which occurs within the incandescent bulb. Some of the tungsten atoms escape the wire and collide with inert gas atoms in the bulb, though they often return to the filament. This cycle reduces the efficiency further as it leads to gradual thinning of the tungsten filament, eventually causing the bulb to fail.