You have 100 m of fine copper wire with a radius of 0.5 mm. Having only a 12 V power supply that can be treated as ideal, a pencil, and a bag of long nails made from 99.8% pure iron (relative magnetic permeability of 200) you need to make a magnet that would produce a strong magnetic field. A. (2 points) What is the resistance of the 100 m of the given copper wire? Assume the resistivity of copper to be LaTeX: \rho=\:1.68\times10^{-8}\:\Omega\cd ot mrho = 1.68 × 10 − 8 Ω ⋅ m. B. (2 points) Assuming that you will use all the wire, what will be electric current if you connect the wire to the power supply? C. (4 points) Would you build a toroid? A solenoid? A simple loop? Justify your choice. D. (6 points) For the chosen design of the magnet, describe how you would build it and estimate the magnetic field that you can achieve with it. g