PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Two infinitely long, straight, parallel wires X and Y are separated by a distance d. They carry currents IX and IY respectively in the same direction.
(i) Derive an expression for the distance x from wire X (measured along the line joining the wires) at which the net magnetic field is zero.
(ii) Using the expression obtained in part (i), calculate x when d=8.0cm, IX=20A and IY=50A. Take μ0=4π×10−7TmA−1.
(iii) Is the point where the magnetic field is zero located nearer to the wire carrying the larger current or the smaller current? Give a brief qualitative reason for your answer.