UPSC 2017 CDS I GK Paper

The capacitance of a parallel plate capacitor is proportional to the surface area A and inversely proportional to the distance d between the two plates and this is true for dielectric medium of air. However, the capacitance value of a capacitor can be increased by inserting a solid medium in between the conductive plates which has a dielectric constant greater than that of air.
The value of capacitance will be 7C.
Capacitance of capacitor C=

∊A

d

where, A is area of plates and d is distance between the two plates.
Now,C=

∊′A

d

=

7∊A

d

Hence,C' = 7C