A core is shown in Figure P16.20, with $\mu_r=2,000$ and $N=100$. Find:
a. The current needed to produce a flux density of $0.4 \mathrm{~Wb} / \mathrm{m}^2$ in the center leg.
b. The current needed to produce a flux density of $0.8 \mathrm{~Wb} / \mathrm{m}^2$ in the center leg.