Question

An electric field of 1500 $Vm^{-1}$ and a magnetic field of
0.40 $Wbm^{-2} $ act on a movirig electron. The minimum
uniform speed along a straight line, the electron could
have is

• A. $1.6 \times 10^{15}ms^{-1} $
• B. $6 \times 10^{-16}ms^{-1}$
• C. $3.75 \times 10^3 ms^{-1} $
• D. $3.75 \times 10^2 ms^{-1} $

Answer 1

Answer: (C)

When electron moves in both electric and magnetic fields
then,
$ qE=qvB $
$ v=\frac {E}{B}= \frac {1500}{0.40} $
$ =3750 \, ms^{-1} $
$ v=3.75 \times 10^3ms^{-1} $