A New Zealand physicist has published a paper that claims to prove that two positively charged metal spheres will almost always attract when placed close enough to one another.
Professor John Lekner from the Victoria University of Wellington claims that if the space between the two spheres is small, relative to the size of the spheres, they will attract.
This is explained by the fact that the electrons within the spheres are able to move, meaning that even though there is an overall positive charge, positive and negative poles can still exist within the sphere. Therefore the positive pole of one of the spheres attracts to the negative pole from the other one.
The effect is not limited to spheres, but the mathematical proof is easier with a spherical shape. This explanation may account for observations that date back as far as 1836, when a researcher called Snow Harris found that two metallic objects with a like charge attracted. While these sort of specific observations have been found, Lekner has created a general theorem to explain the effect.
It is actually more likely for them to attract than repel: only one situation creates repulsion and that is when the ratio of the charges is identical to that of when the spheres are in contact and charge is able to flow. In that situation, each sphere would have the same voltage and if they both have the same voltage, then they will repel at any distance.
This new mathematical proof of the effect is likely to impact research in many other situations where there is charge separation and static electricity, such as droplets in clouds or particles of carbon in flames.
Don’t you love it when something you learned in highschool science as an ‘absolute’ can suddenly be turned on its head? Welcome to the world of more advanced physics: the further you go, the more exceptions to the rules you see!