In a certain region static electric and magnetic fields exist. The magnetic field is given by B = B_0( i +2 j -4 k ). If a test charge moving with a…

In a certain region static electric and magnetic fields exist. The magnetic field is given by $\displaystyle \overrightarrow{\mathrm{B}}=\mathrm{B}_0(\hat{i}+2 \hat{j}-4 \hat{k})$. If a test charge moving with a velocity $\displaystyle \vec{v}=v_0(3 \hat{i}-\hat{j}+2 \hat{k})$ experiences no force in that region, then the electric field in the region, in SI units, is :