Practice portal › Moving Charges and Magnetism › Force on a Current-Carrying Conductor
Asked in RS Academy GUJCET booklet · Force between parallel currents
Given: a circular loop of wire lying in the XY plane and carrying a current I, with no other field present.
Idea: every element of the ring sits in the magnetic field produced by the rest of the ring, and feels I d⃗l×⃗B.
At the wire itself the field of the far side of the loop is directed so that this force points radially outward, away from O.
The same thing in terms of currents: across a diameter the two sides carry current in opposite senses, and antiparallel currents repel.
So the ring is stretched from the inside and tends to expand. Those radial forces cancel in pairs, so the loop as a whole does not move.
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