Question 59 of 227

A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength $20 {\mathrm{Vm}}^{-1}$ and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons

(a) 20 ${\mathrm{ms}}^{-1}$                  (b) 40 ${\mathrm{ms}}^{-1}$ 
(c) 8 ${\mathrm{ms}}^{-1}$                    (d) 5.5 ${\mathrm{ms}}^{-1}$