• # question_answer An air filled parallel plate capacitor has a capacity of 2pF. The separation of the plates is doubled and the interspace between the plates is filled with wax. If the capacity is increased to 6pF, the dielectric constant of wax is : A)  2                                 B)  3 C)  4                                 D)  6

Capacitance with air, $C=\frac{A{{\varepsilon }_{0}}}{d}$ When interspace between the plates is filled with wax, then             $C'=\,\frac{KA{{\varepsilon }_{0}}}{2d}\,\,or\,C''\,=\left( \frac{A{{\varepsilon }_{0}}}{d} \right)\,\frac{K}{2}$                      $C''=C\frac{K}{2}\Rightarrow 6=2\times \frac{K}{2}\,=K=6$