Question

A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength $20\mspace{6mu} Vm^{- 1}$and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons.

• A. 20 $ms^{- 1}$
• B. 40 $ms^{- 1}$
• C. 8 $ms^{- 1}$
• D. 5.5 $ms^{- 1}$

Answer 1

Answer: (B)

40 $ms^{- 1}$

Answer 2

$v = \frac{E}{B} = \frac{20}{0.5} = 40m/sec.$