Question

A charge particle having mass m and charge $+q$, given a velocity $\overrightarrow{V_0}=2\stackrel{-}{i}+4\stackrel{-}{j}m/s$ in a region where electric field and magnetic field exists. Magnetic field in the region is $\overrightarrow{B}=6\stackrel{-}{i}-8\stackrel{-}{j}$ (Tesla). It is observed of charged particle remains constant. Electric field in the region is:

• A. $50N/C$
• B. $40N/C$
• C. $30N/C$
• D. $60N/C$

Answer 1

The correct option is B $40N/C$

since the particle remains constant,net force due to both the fields is zero

$Eq=q(v\times B)$

$E=(2\hat{i}+4\hat{j})\times (6\hat{i}-8\hat{j})=-40\hat{k}$

E=40N/C