People today seem to have only a vague notion of how traffic lights detect that they are sitting in their car at an intersection waiting for the light to change. I’m happy to report that once again we see the power of the magnetic field being harnessed in a simple and effective manner (unless you happen to not have a lot of metal, like, say bicycles). I mentioned before that I think magnetic fields are cool – but here’s an example we come across almost every day without realizing it.
No, your car’s weight does not trigger the light – its your car’s metal content. Here’s an article from Howstuffworks that explains it for those of you interested. Now armed with this information you can start looking at intersections for those induction coils hidden in the road (black ribbons about an inch wide, usually a circle or square). You’d be surprised how easy it is to always get the advance turn filter once you know where to stop in the lane….
I wonder how well this will work with new cars using more plastics and non magnetic materials like carbon fiber and ceramics?
I can’t believe it took you this long to inform the masses!!!
(I’m also impressed you took an informative tone, rather than the “How can you people be so stupid” tone that I have occasionally heard when we sit behind some ‘mass’ who has missed the trigger!)