You asked this already.
I find multiple posts annoying.
Two parallel wires carry currents in the same direction. I1=3A and I2=1A and the distance between the conductors is 4 cm. The magnetic field midway between these two wires is
2 answers
f/1=u.l1l2/2πd
f=4π*10^-7/2π*4
f=4*10^-7/8
f=5*10^-8N
f=4π*10^-7/2π*4
f=4*10^-7/8
f=5*10^-8N
1 answer