Question

Two horizontal wires separated by a distance of 0.5 m both carry a current to the left. The upper wire has a current of 15A while the lower wire has a current of only 3A. What is the force per unit lenght on the upper wire? (show your work including equation and units)

Answer 1

  two long straight parallel wires separated by a distance d carrying currents I₁ and I₂ .

$$\displaystyle{\frac{F_2}{l}}$$ = $$\displaystyle{\frac{\mu_0I_1I_2}{2\pi d}}$$

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the force per unit length of the wire is F/l = (4 pi x10^-7 x i1 x i2 )/( pix r)

= 2x10^-7 x15x3 / 0.5

=1.8 x10^-5 N/m.