An electron moving with a velocity $v=(5\mathrm{.}0{10}^7)i\frac{m}{s}$ enters a region of space where perpendicular electric and magnetic fields are present. The electric field is $E=-{10}^{4}j.$ What magnetic field will allow the electron to go through the region without being deflected?

$B=(+2\mathrm{.}0{10}^{-4}(T))j$

$B=(+2\mathrm{.}0{10}^{-4}(T))k$

$B=(-2\mathrm{.}0{10}^{-4}(T))k$

$B=(+5\mathrm{.}0{10}^{-4}(T))k$

$B=(-2\mathrm{.}0{10}^{-4}(T))j$