Question

The capacity of a parallel plate capacitor with no dielectric substance but with a separation of $0.4cm$ is $2\mu F$. If the separation is reduced to half and it is filled with a dielectric substance of value $2.8$, then the final capacity of the capacitor is

• A. $11.2\mu F$
• B. $15.6\mu F$
• C. $19.2\mu F$
• D. $22.4\mu F$

Answer 1

Answer: (A)

$11.2\mu F$

Given, $C=\frac{{\epsilon }_{0}A}{d}=2\mu F$
and $C^{\prime }=\frac{K{\epsilon }_{0}A}{d^{\prime }}=\frac{2.8{\epsilon }_{0}A}{d/2}=\frac{5.6{\epsilon }_{0}A}{d}$
$\Rightarrow C^{\prime }=5.60\times 2=11.2\mu F$