Question

A positively charged particle of $2.0C$ moves upward into an area where both a magnetic field and an electric field are acting. The magnetic field has a magnitude of $4.0\times {10}^{4}T$ and the electric field has a magnitude of $0.1N/C$. At what velocity must the particle be moving if it is not deflected when it enters this area?

• A. $4.0\times {10}^{-3}m/s$
• B. $125m/s$
• C. $250m/s$
• D. $500m/s$
• E. The particle will be deflected to the left regardless of its velocity

Answer 1

The correct option is C $250m/s$

$Balancingtheelectrostaticandmagneticforceweget$
$F=qE=qvB$
$\Rightarrow v=\frac{E}{B}=\frac{0.1}{4\times {10}^{-4}}$
$=250m/s$