\(B=\frac{\mu_{0} e v}{4 \pi r^{2}}\)

Substitute \(4 \pi \times 10^{-7}\) for \(\mu_{0}, 1.6 \times 10^{-19}\) for \(e 2.18 \times 10^{6}\) for \(v\) and \(25 \times 10^{-11}\) for \(r\)

\(B=\frac{\left(4 \pi \times 10^{-7}\right)\left(1.6 \times 10^{-19}\right)\left(2.18 \times 10^{6}\right)}{4 \pi\left(25 \times 10^{-11}\right)^{2}}\)

\(=\frac{1.6 \times 2.18}{25} \times 10^{2}\)

\(=13.95 \,T\)