A parallel plate capacitor made to circular plates each of radius R = 6 cm has capacitance C = 100 pF. The capacitance is connected to a 230V A.C. supply with an angular frequency of 300 rad/s., the value of B at a point 3 cm from the axis between the plates will be:

1.63 × 10^–11 T

$B_0 =\frac{\mu_0\left(I_{D}\right)_{\text {peak }} r}{2 \pi R^2}$

$=\frac{2 \times 10^{-7} \times \sqrt{2} \times 6.9 \times 10^{-6}}{2 \times 3.14 \times 36 \times 10^{-4}} $

$=1.63 \times 10^{-11} T$