Inside a parallel plate capacitor the electric field E varies with time as $t^2$. The variation of induced  magnetic field with time is given by :

For a given plate circumference = L (constant ) and area of plate = A (constant)

$\begin{array}{l}\int Bdl={\mu }_0{i}_D={\mu }_0{\epsilon }_0\frac{d{\varphi }_E}{dt}\\ BL={\mu }_0{\epsilon }_{0}A\frac{dE}{dt}\\ B\propto \frac{dE}{dt}\\ \frac{dB}{dt}\propto \frac{d^{2}E}{d{t}^2}\text{........(1)}\\ E=k{t}^2\\ \frac{dE}{dt}=2kt\\ \frac{d^{2}E}{d{t}^2}=2k=cons\tan t\\ \Rightarrow \boxed{\frac{dB}{dt}=cons\tan t}\end{array}$