A square frame of wire connected to a capacitor is kept in a magnetic field which varies with position as well as time and is given as $\overrightarrow{B}=axt\left(-\overrightarrow{k}\right)$ as shown in figure, where $\alpha$ is a constant. The charge on the capacitor at any time is $\frac{n}{2}C\alpha l^3$ . Then find the value of ‘n’.