A question from H C Verma part 2 – electric field and potential. Question for short answer – #3

Consider 2 particles A and B having equal charges and placed at some distance. The particle A is slightly displaced towards B. Does the force on B increase as soon as the particle A is displaced? Does the force on A increase as soon as soon as it is displaced?

I think answer to both should be yes, but it appears too easy so i think I am missing something, maybe it is easy, I just wanted to check. Thanks for your help.

Yes immediatelyBT I don`t calculate thatThTh b work doneU fifind final force value after displacementy

I think the force on B Due to A will not increase as soon as particle A is displaced. This is because the electric field of A will take some time to propagate. The electric field at a distance R from A will take time R/C where C is the speed of light to displace. Whereas B is not displaced so there will not be any displacement of its electric field.

No, the force on B will not suddenly increase as A is displaced towards it because the electric field of A will take some finite time to move from its position. The electric field of A at a distance r from A will know that A has moved from its position after r/c seconds where c is the speed of light. It will start displacing itself r/c seconds when the particle A began to displace. So after r/c seconds B will start experiencing force from A. Whereas the particle B has no displacement so there is no need to its electrical field to move and A will experience the the force from B at the time it is displaced.

Yes, the force on both will be increased, if the charges are not moving they are in rest(stationery). So, that`s it.