Question

An electric field of intensity $6\times {10}^{4}volts/m$ is applied perpendicular to the direction of motion of the electron. A magnetic field of intensity $8\times {10}^{-2}wb/m^2$ is applied perpendicular to both the electric field and direction of motion of the electron. What is the velocity of the electron if it passes undeflected?

• A. $7.5\times {10}^{5}m/s$
• B. $7.5\times {10}^{-5}m/s$
• C. $6\times {10}^4\times 8\times {10}^{-2}m/s$
• D. It is never possible

Answer 1

The correct option is A $7.5\times {10}^{5}m/s$

In case of no deviation, $eE=evB$
$\therefore v=\frac{E}{B}=\frac{6\times {10}^4}{8\times {10}^{-2}}$

$=7.5\times {10}^{5}m/sec.$