Question

Why are attractive fields considered negative?

Answer 1

u mean NEGATIVE POTENTIAL ?

cause .. we always choose potential to be zero at a point where we are free from the evil clutches of those fields (which is not really a compulsion u are free to choose wherever u please) and that always turns out to be infinity..

also you should know when u go ALONG THE FIELD LINES POTENTIAL ALWAYS DECREASES.. eg. drop a ball, ball goes along the g field, and its potential energy decreases..

so when u combine these two things what do u get?


if u have attractive field lines, as u go from infinity to finite world, u would have travelled ALONG the field line and so ur pot decreases, but u had zero to start with (infinity = zero potential) hence u end up with negative potential

similarly if u had a repulsive field, then when u go from infinity to finite world, u would go AGAINST the field increasing ur Pot, and thus ur pot becomes POSITIVE!. .


but absolute potential doesn't matter at all. . its always change in potential that matters, so never worry too much about -ve or +..

-ve potential energy is called as bound state by the way!