Question

An air filled parallel plate capacitor has a capacitance $1pF$. The separation between the plates is doubled and wax is inserted between the plates, then the capacitance becomes $2pF$. What is the dielectric constant of wax ?

• A. $8$
• B. $2$
• C. $4$
• D. $16$

Answer 1

The correct option is C $4$

Capacitance of parallel plate capacitor with air ,$C_a=\frac{{\epsilon }_{0}A}{d}....\left(1\right)$

Capacitance of parallel plate capacitor with wax ,$C_w=\frac{K{\epsilon }_{0}A}{2d}.....\left(2\right)$

$\left(1\right)/\left(2\right),$

$\frac{C_a}{C_w}=\frac{2}{K}$

$\frac{1}{2}=\frac{2}{K}$

$\therefore K=4$