An electron (mass 9 × 10^-31 kg and charge 1.6 × 10^-19 C ) moving with speed c / 100 ( c = speed of light ) is injected into a magnetic field B of…

An electron (mass $\displaystyle 9 \times 10^{-31} \mathrm{~kg}$ and charge $\displaystyle 1.6 \times 10^{-19} \mathrm{C}$ ) moving with speed $\displaystyle \mathrm{c} / 100$ $\displaystyle (\mathrm{c}=$ speed of light $\displaystyle )$ is injected into a magnetic field $\displaystyle \vec{B}$ of magnitude $\displaystyle 9 \times 10^{-4} \mathrm{~T}$ perpendicular to its direction of motion. We wish to apply an uniform electric field $\displaystyle \vec{E}$ together with the magnetic field so that the electron does not deflect from its path. Then (speed of light $\displaystyle \mathrm{c}=3 \times 10^8 \mathrm{~ms}^{-1}$ )