Question: How do lasers burn stuff? I am in junior infants

Padraic Morrissey answered on 9 Feb 2015:

That’s another great question from students in infants, ye must be very bright! To explain how lasers work you need to get an idea first about how the work. I explained that in one of my other questions so I’ll put it here too.

When you turn on a light switch, the light from the bulb is spread out in all directions across a room and you can see. Something different happens when you turn on a laser though, instead of being spread out all over the room, the light is focussed onto a really small point. That’s why they are used as laser pointers!

Mirrors are used to focus the light, and every laser must have at least two mirrors to work properly. What happens is, the light hits off one mirror, gets reflected onto the other, and then bounces back to the first mirror. This happens millions of times every second (because light moves so fast) and you end up with a really bright light in between the mirrors because of all the bouncing around.

This really bright light leaves the laser as a very focussed beam and can be very hot due to the build up of energy. If the laser is strong enough it can actually burn and cut through metal!

I hope that answers your question, if there’s any bits I haven’t explained properly let me know!