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。

youdao

The light bulb that we have here is only a few watts.

我们这的电灯泡，只不过是几瓦。

youdao

REMEMBER the urban myth about the inventor who patented a light bulb that would last for ever, only to see the patent snapped up by a consortium of manufacturers who buried it for good?

大家是否还记得这样一个都市神话？ 一位发明者申请了永亮灯的专利，结果是专利被灯具制造商们联合买断，之后为了利益，制造商们把专利销毁了。

youdao

The output from a single workout is only enough to power a light bulb or a laptop for about an hour and saves between two to six ounces of CO2.

CNN: Virtuous cycles