Question

An electron moving with a velocity = 5.0 × 10 7 m/s enters a region of space where perpendicular electric and a magnetic fields are present. The electric field is = . What magnetic field will allow the electron to go through the region without being deflected?

Answer 1

Answer:

The magnetic field is $2 \times 10^{-4}$ T

Explanation:

Given:

Velocity of electron $v = 5 \times 10^{7} \frac{m}{s}$

Electric field $E = 10^{4} \frac{V}{m}$

The force on electron in magnetic field is given by,

 $F = qvB \sin \theta$                      ......(1)

The force on electron in electric field is given by,

 $F = qE$                               ......(2)

Compare both equation,

   $qE = qvB \sin \theta$

Here $\sin \theta = 1$

  $E = vB$

  $B= \frac{E}{v}$

  $B = \frac{10^{4} }{5 \times 10^{7} }$

  $B = 2 \times 10^{-4}$ T

Therefore, the magnetic field is $2 \times 10^{-4}$ T