A positively charged particle $\left[\text{specific\hspace{0.17em}charge\hspace{0.17em}}\frac{\text{q}}{\text{m}}\text{=1}\right]$ is projected in xy plane with speed 4 m/s in a gravity free space having uniform electric field $\overrightarrow{E}=-E_0\widehat{j}$ .Uniform magnetic field $\overrightarrow{B}=-B_0\widehat{j}$  is also switched on in the space at t = 0 when speed of charged particle was minimum. During motion of charge particle if $Z_{\max }$ is maximum possible z-coordinate and if at ${\text{t=t}}_{\text{1}}$  charge particle again touches the x-y plane, then