Question

An electron beam moving with a speed of $2.5\times {10}^{7}m{s}^{-1}$ enters into the magnetic field directed perpendicular to its direction of motion. The magnetic induction of the field is $4\times {10}^{-3}wb/m^2$. The intensity of the electric field applied so that the electron remains undeflected due to the magnetic field is.

• A. ${10}^{4}N/C$
• B. ${10}^{5}N/C$
• C. ${10}^{7}N/C$
• D. ${10}^{3}N/C$

Answer 1

Answer: (B)

${10}^{5}N/C$

For no deflection
VB = E
$\to E=2.5\ast {10}^7\ast 4\ast {10}^{-3}$
$=10\ast {10}^4$
$={10}^{5}N/C$