The two wires shown in the figure below we separated by d 1

The two wires shown in the figure below we separated by d = 11.7 cm and carry currents of t = 4.55 A in opposite directions. Find the magnitude and direction of the net magnetic field at a point midway between the wires. Find the magnitude and direction of the net magnetic field at point P_1. 11.7 cm to the right of the wire on the right.

Solution

At the point half way between the two wires

B_net = -B₁ - B₂ = [-mu₀ / 2 pi r] [I₁ + I₂]

= [-4 pi * 10^-7 / 2 pi * 5.85 * 10^-2] [9.1]

= -3.11 * 10-5 T

B_net = -31.1 muT into the page

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B_net = B₁ - B₂ = [mu₀ / 2 pi ] [I₁/r₁ - I₂/r₂]

= [4 pi * 10^-7 / 2 pi ] [4.55/0.117 - 4.55/0.234]

= 3.84 * 10^-5 T out of page