if oxygen feeds fire, why does a strong dose kill it? you know, like blowing out a candle? shouldn't that make things worse?
In large amounts it could make it very difficult for you to breathe, but according to a source I looked up, it's not harmful because the contents of the fire extinguisher is non toxic. But I would have to question why someone would do this in the first place. If it's kept out of the reach of children and babies, there shouldn't be a problem if it's stored right. That means the safety pin has to be in place to keep it from discharging accidentally, so you don't accidently spray it where it shouldn't be. The link below answers some other questions about fire extinguishers. We all had to learn to use one at work in case there was a fire which we COULD control. So the fire department taught us the features of the extinguisher, and how to use it properly.
I think you mean lightning rod. The basic shape is a spike, pointing up towards the sky. The way it works is that the electrically-charged particles in the air induce an opposite charge on the spike. Usually, this attracts the charge in the air which then leaks down the conductor safely to earth. This is when the lightning rod is doing its job and protecting the building. On odd occasions, like during intense storms, the build-up of electrical charge is so great that the insulating properties of the air break down. The electric charge is then discharged in a very short space of time and is seen as a flash of lightning. The resultant heat of the discharge can melt the metal of the rod. Some lightning rods have a ball shape some way below the spike. I think this is intended to improve the effectiveness of the rod by varying its surface area, thereby controlling the rate of flow of the electrical charge . I suspect that other shapes are intended to have much the same effect and are the result of experimentation.
they should be shaped like a spike. Any other shape is just for decoration, aesthetics purposes, probably at the discretion of the archetect.
