Q.
The capacitance of a parallel plate capacitor with air as medium is 3μF. As a dielectric is introduced between the plates, the capacitance becomes 15μF. The permittivity of the medium in C2N−1m−2 is
The capacitance of air capacitor is given by C0=dε0A=3μF....(i)
When a dielectric of permittivity εr and dielectric constant K is introduced between the plates, then C=dKε0A=15μF...(ii)
Dividing Eq. (ii) by Eg. (i), we get C0C=dε0AdKε0A=315 ⇒K=5
So, the permittivity of the medium εr=ε0K =8.85×10−12×5 =0.44×10−10