Max Arthur Cohn's painting "Coal Tower" shows the dark form of a coal tower against a light sky.

VOA: special.2009.03.23

That makes sense because we're losing energy, we're going to a level lower level, so we can give off that extra in the form of light. And we can actually write the equation for what we would expect the energy for the light to be.

这很合理，因为我们在损失能量,我们要到一个更低的能级去,我们要以光的形式给出额外的能量,我们可以写下光能量的方程。

麻省理工公开课 - 化学原理课程节选

Acquiring this simple and non-polluting form of electric light,he points out, promotes education, public health,economic security and a cleaner environment.

VOA: standard.2009.12.13