(Solved): An electron moves in a circle of radius r=4.291011m with speed 2.00106m/s. Treat the cir ...

An electron moves in a circle of radius $r=4.29\times 10^{-11}\mathrm{m}$ with speed $2.00\times 10^6\mathrm{m}/\mathrm{s}$. Treat the circular path as a current loop with a constant current equal to the ratio of the electron's charge magnitude to the period of the motion. If the circle lies in a uniform magnetic field of unknown magnitude. If the maximum torque experienced by the electron is $4.19\times 10^{-26}$ ${\mathrm{N}}^{\ast }\mathrm{m}$, what is the magnitude of the magnetic field? $\begin{array}{l}3.10\times 10^{-3}\mathrm{T}\\ 4.20\times 10^{-3}\mathrm{T}\\ 1.50\times 10^{-3}\mathrm{T}\\ 6.10\times 10^{-3}\mathrm{T}\\ 2.10\times 10^{-3}\mathrm{T}\end{array}$