Q27. An electron with kinetic energy 5 eV enters a region of uniform magnetic field of $3 \mu \mathrm {~T}$ perpendicular to its direction. An electric field E is applied perpendicular to the direction of velocity and magnetic field. The value of $E$, so that electron moves along the same path, is $\_\_\_\_$ $\mathrm { NC } ^ { - 1 }$. (Given, mass of electron $= 9 \times 10 ^ { - 31 } \mathrm {~kg}$ , electric charge $= 1.6 \times 10 ^ { - 19 } \mathrm { C }$ )