Question

A particle of charge $-16\times {10}^{-18}$ coulomb moving with velocity 10 m/s along the x-axis enters a region where a magnetic field of induction B is along the y-axis, and an electric field of magnitude ${10}^{4}V/m$ is along the negative z-axis. If the charged particle continues moving along the x-axis, the magnitude of B is

• A. ${10}^{-3}Wb/m^2$
• B. ${10}^{3}Wb/m^2$
• C. ${10}^{5}Wb/m^2$
• D. ${10}^{16}Wb/m^2$.

Answer 1

The correct option is B ${10}^{3}Wb/m^2$

Particles is moving undeflected in the presence of both electric field as well as magnetic field. So its speed is,
$v=\frac{E}{B}\Rightarrow B=\frac{E}{v}=\frac{{10}^4}{10}={10}^{3}Wb/m^2$.