A parallel plate capacitor as shown in the figure is made of circular plates each of radius $R = 6\: cm$, and it has a capacitance $C = 100\: pF$. The capacitor is connected to a $230\: V$ ac supply with a frequency of 300 rad/s. The amplitude $B$ at a point $3\: cm$ from the axis between the plates is

Question

 

$\begin {array} {1 1} (a)\;16.3 \times 10^{-11}T & \quad (b)\;16.3 \times 10^{-13}T \\ (c)\;1.63 \times 10^{-11}T & \quad (d)\;1.63 \times 10^{-13}T \end {array}$