If you needed another reason to avoid Psychic Fairs…

In the UK, a woman managed to avoid tragedy when her flat caught fire while she was out visiting a friend. What makes this story interesting (for our purposes) is that her tale highlights some lovely, basic chemistry and physics concepts which we can all learn from without having to experience it for ourselves...

Fire: a chemical reaction that occurs when a flammable material is exposed to significant heat in the presence of an oxidiser (like oxygen).

All fires require four things – heat, fuel, oxygen (or another oxidiser) and the ability to start a chain reaction. This is known as the fire tetrahedron.

There are a lot of ways to increase temperature – for example, matches work by using friction between the surface of the match and the matchbox to heat the lovely, flammable phosphorus on their tips. Ovens and microwaves create an artificially warm environment which can create an optimum environment for a fire. Striking two rocks together (like quartz and pyrite) creates enough friction to create a spark.

In this case, the increase in temperature was caused by a ₤20 crystal ball.

Refraction: the change in direction of a wave (light waves, for example) when it’s speed changes, often as the result of passing into another medium (like a crystal ball).

The crystal ball was given pride of place on the windowsill. On a particularly sunny day, as the owner was out walking with a friend, the light streamed down and hit the crystal ball. As the sunlight passed through the crystal ball, it refracted or bent. In fact, the crystal ball bent all the sunlight so that it was focused towards a single point, much like the magnifying glass in this unfortunate incident. With all the light waves working together, that single point started to get very, very hot.

Unfortunately, that single point also happened to be focused on the curtains. Curtains tend to be fairly flammable. As do sofas. And cushions. And books. And a lot of the other items a typical person would have in their lounge room.

Explosion: a rapid increase in volume which creates a shock wave, often generating very high temperatures and releasing gases. (ie something gets very big, very quickly).

To add insult to injury, the woman had left an old television set on the sofa. According to the newspaper reports, the set blew up ‘creating a noise that could be heard several streets away.’

Science 2. Crystal ball aficionados 0.