The capacitance of an filled parallel plate capacitor is 20 µµF. The separation between the plates is doubled and the space between the plates is then filled with wax giving the capacitance a new value of 40 × 10⁻¹² farads. The dielectric constant of wax is

8.0

$10 \times 10^{-12}=\frac{\varepsilon_0 A}{d} . 40 \times 10^{-12}=\frac{K \varepsilon_0 A}{2 d}$

∴ K = 8

∴ (C)