The space has electromagnetic field which varies with time whose variation is given as
$\overrightarrow{B}=\left\{\begin{array}{ccc}-{\text{B}}_0\widehat{k}& \text{ if }& 0\le t\le \frac{\pi \text{m}}{{\text{qB}}_0}\\ -{\text{B}}_0\widehat{j}& \text{ if }& \frac{\pi \text{m}}{{\text{qB}}_0}<t\le \frac{2\pi \text{m}}{{\text{qB}}_0}\\ 0& \text{ if }& \frac{2\pi \text{m}}{{\text{qB}}_0}<t<\infty \end{array}\right.$          
and  $\overrightarrow{\text{E}}=\{\begin{array}{ccc}0& \text{ if }& 0\le t\le \frac{2\pi \text{m}}{{\text{qB}}_0}\\ -{\text{E}}_0\widehat{k}& \text{ if }& \frac{2\pi \text{m}}{{\text{qB}}_0}<t<\infty \end{array}$
A charge particle having mass m and positive charge q is given velocity  ${\text{v}}_0\widehat{i}$ at origin at $t=0$  sec. The coordinate of point on xy plane when it is passing through xy plane again is