But as some of the excited electrons fall back to their ground states, they emit energy as light.

不过当一部分的激发电子回到它们的基态的时候，它们会释放出能量，即光。

When these excited electrons fall back to their normal energy levels, their excess energy is carried away by photons, or particles of light.

当这些激发态的电子回到它们的正常能级时，它们多余的能量会被光子或光粒子带走。

Atoms in most metals tend to give up electrons really easily, so when heat or electricity run through a piece of metal that's basically a stream of excited electrons.

大多数金属的原子很容易失去电子，所以当热或电穿过一片金属时，那基本上是一股活跃的电子。