Question: How do lasers form?

Paul O'Mahoney answered on 7 Mar 2016:

This is quite a hard one to explain actually! Inside a laser is a cavity that has lots of one kind of element in it (so maybe things like Argon, or Helium and Neon). What you do is give the elements in the cavity some electricity and they turn that electricity in to light! Different elements can give out different colours of light, so that’s why you can get green, blue and red lasers.