Question

Two long straight wires separated by 8 cm carry currents of equal magnitude but heading in opposite directions. The wires are shown perpendicular to the plane of this page. Point P is 2 cm from wire 1, and the net magnetic field at point P is 1x10-2 T directed in the negative y direction. What is the magnitude of the current in wire 1 in A units)? wire i Wire 2

Answer 1

here,

the seperation between the wires , d = 8 cm = 0.08 m

r1 = 2 cm = 0.02 m

let the magnitude of current in each wire be I

the magnetic field at point P , B = u0 * I /(2*pi*r1) + u0* I /(2*pi*(d - r1))

1 * 10^-2 = 1.26 * 10^-6 * I /(2*pi) * ( 1/0.02 + 1/(0.08 - 0.02))

solving for I

I = 748 A

the magnitude of current in wire 1 is 748 A