question_answer

A beam of electrons is moving with constant velocity in a region having simultaneous perpendicular electric and magnetic fields of strength \[20\,V{{m}^{-1}}\] and 0.5 T respectively at right angles to the direction of motion of the electrons. Then the velocity of electrons must be

A) \[8\,m/s\]

B) \[20\,m/s\]

C) \[40\,m/s\]

D) \[\frac{1}{40}\,m/s\]