Answer
$E^{\prime}=2.1K\frac{V}{m}$
Work Step by Step
Let $E^{\prime}$ be the Electric Field in dielectric itself.
Then $E^{\prime}=\frac{E}{\epsilon_r}$
Putting the values into this formula, we get
$E^{\prime}=\frac{10\times10^3}{4.8}=2083=2.083\times10^3=2.1K\frac{V}{m}$
