JEE PHYSICS MCQ: ELECTROMAGNETIC WAVES

A particle of specific charge $\left(\frac{\text { charge }}{\text { mass }}\right) \alpha$ start moving from origin under action of an electric field $\vec{E}=E_0 \hat{i}$ and magnetic field $\vec{B}=B_0 \hat{k}$. Its velocity at $\left(x_0, y_0, 0\right)$ is $4 \hat{i}+3 \hat{j}$. The value of $x_0$ is