28. Magnetic Fields and Forces

A loop of wire with a radius of $2.0\mathrm{cm}$ lies in the $xy$ -plane and is centered on the origin. It carries a counterclockwise current of $1.0$ A when viewed from above the $xy$ -plane. A long, straight wire lies along the line $y=-2.0\mathrm{cm}$. so that it is tangent to the lowest point on the loop. This straight wire carries a current of $1.0\text{A}$ in the negative x-direction. What is the strength of the magnetic field at the center of the loop?

Consider current I passing through a resistor of radius r, length L, and resistance R. a. Determine the electric and magnetic fields at the surface of the resistor. Assume that the electric field is uniform throughout, including at the surface.