A beam of electrons is moving with constant velocity in a region having simultaneous perpendicular electric and magnetic fields of strength 20 Vm-1 and 0.5 T respectively at right angles to the direction of motion of the electrons. Then the velocity of electrons must be
1
8 m/s
2
20 m/s
3
40 m/s
4
\(\frac{1}{40}\) m/s