Physics - Capacitor Question with Solution | TestHub

Initial effective capacity of the parallel combination of two identical capacitors is $C_i=C+C=2C$.

When one of the capacitors is completely filled with a dielectric material of constant $K$, its new capacity becomes $KC$.

The final effective capacity of the parallel combination is $C_f=KC+C=C(K+1)$.

The change in the effective capacity is $\Delta C=C_f-C_i$.

Substituting the values, we get $\Delta C=C(K+1)-2C=CK+C-2C=C(K-1)$.

Answer: $\mathrm{C}(\mathrm{K}-1)$