(b) $I_{D} = \varepsilon_{0}\frac{d\phi_{E}}{dt} = \varepsilon_{0}\frac{EA}{t} = \varepsilon_{0}\left( \frac{V}{d} \right).\frac{A}{t}$
$= \frac{8.85 \times 10^{- 12} \times 400 \times 60 \times 10^{- 4}}{2 \times 10^{- 3} \times 10^{- 6}} = 1.602 \times 10^{- 2}amp$