I recently encountered a question which went like this,
A current-carrying loop is placed in a plane perpendicular to a long current carrying wire at a distance from it. What is the force acting on the loop?
The answer was given to be zero for any shape of the loop.
I couldn't find a convincing reason for this and it left me puzzling.
Is the answer right? If yes, how and if not, why?
Integrating all over the loop is fine for a regular shape but the question is about any shape of the loop.