An incandescent bulb, made of a wire filament encased in glass, emits only 5% of the energy it consumes as light; the rest is wasted as heat.
An incandescent bulb, made of a wire filament encased in glass, emits only 5% of the energy it consumes as light; the rest is wasted as heat.
由灯丝封装在玻璃里而制成白炽灯，只有5％的能量被用于发光；其余都以热能被浪费掉了。