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# A parallel plate capacitor has circular plates, each of radius $5\: cm$. It is being charged so that electric field in the gap between its plates rises steadily at the rate of $10^{12}V/ms$. What is the displacement current?

$\begin {array} {1 1} (a)\;0.1A & \quad (b)\;0.7A \\ (c)\;0.07A & \quad (d)\;0.01A \end {array}$

$Id = \in_o \large\frac{d \phi_E}{dt}$$= \in_o \large\frac{d(EA)}{dt}$$ = \in_oA \large\frac{ dE}{dt}$$= \in_o\large\frac{ \pi r^2 dE}{dt}$
$= 8.85 \times 10^{-12} \times 3.14 \times 25 \times 10^{-4} \times 10^{12}$
$= 0.07 A$
Ans : (c)

edited Mar 3, 2014