d
\(P = \frac{{{e^2}}}{R};\;\;e = - \frac{d}{{dt}}(BA) = A\frac{d}{{dt}}({B_o}{e^{ - t}}) = A{B_o}{e^{ - t}}\) \( \Rightarrow P = \frac{1}{R}{(A{B_o}{e^{ - t}})^2} = \frac{{{A^2}B_o^2{e^{ - 2t}}}}{R}\) t = 0 \(P = \frac{{{A^2}B_o^2}}{R}\) \( \Rightarrow P = \frac{{{{(\pi {r^2})}^2}B_o^2}}{R} = \frac{{B_o^2{\pi ^2}{r^4}}}{R}\)