Question

In the capacitor of capacitance $20\mu F$, the distance between plates is $2mm$. If a material of dielectric constant $2$ is inserted between the plates, then the capacitance of the system is :

• A. $20\mu F$
• B. $30\mu F$
• C. $22\times 5\mu F$
• D. $40\mu F$

Answer 1

The correct option is D $40\mu F$

We know
$C=\frac{{ϵ}_{0}A}{d}$
When k is added
$C_1=\frac{k{ϵ}_{0}A}{d}$
$\Rightarrow C_1=2\times 20$
$\Rightarrow C_1=40\mu F$