Consider a large parallel plate capacitor. The gap $d$ between the two plates is filled entirely with a dielectric slab of relative permittivity $5$. The plates are initially charged to a potential difference of $V$ volts and then disconnected from the source. If the dielectric slab is pulled out completely, then the ratio of the new electric field $E_{2}$ in the gap to the original electric field $E_{1}$ is ________.