1. The problem statement, all variables and given/known data Two thin coils of radius R = 3 cm are d = 13 cm apart and concentric with a common axis. Both coils contain 10 turns of wire with a conventional current of I = 3 amperes that runs counter-clockwise as viewed from the right side (see the figure). (a) What is the magnitude and direction of the magnetic field on the axis, halfway between the two loops, without making the approximation z >> r? (For comparison, remember that the horizontal component of magnetic field in the United States is about 2 ✕ 10-5 tesla). |B| = _ T direction: c (b) In this situation, the observation location is not very far from either coil. Calculate the magnitude of the magnetic field at the same location, using the 1/z3 approximation. |Bapprox| = _ T The percent error of an approximate result can be found by . What percentage error results if you calculate the magnetic field using the approximate formula for a current loop instead of the exact formula? percent error: _ % (c) What is the magnitude and direction of the magnetic field midway between the two coils if the current in the right loop is reversed to run clockwise? magnitude: _ direction: _ 2. Relevant equations |B| = (mu_0 / 4pi) * (I * R^2 * 2pi) / (R^2 + z^2)^(3/2) |B_approx| = (mu_0 / 4pi) * (2 * I) / r mu_0 / 4pi = 1e-7 R = radius r = distance from ring z = distance from center of ring along z-axis 3. The attempt at a solution I tried using the |B| formula with I = 30 (3A * 10 turns of wire), R = 0.03 m, z = d/2 = 0.065 m. I got 4.6238e-5 T as my answer and it was wrong. This seems too large. Do I need to include the other wire loop, by adding? Do I need to keep I = 3 A?