Q 12-02-119JEE MainJEE Main 2022 (25 Jul, Shift 2)Medium
Two parallel plate capacitors of capacity $C$ and $3C$ are connected in parallel combination and charged to a potential difference $18\ \text{V}$. The battery is then disconnected and the space between the plates of the capacitor of capacity $C$ is completely filled with a material of dielectric constant $9$. The final potential difference across the combination of capacitors will be ______ V.
Numerical value type. Enter your answer.
Answer: 6
Charge $Q = (C + 3C)\times18 = 72C$ stays constant. New capacitance $= 9C + 3C = 12C$.
$$V = \frac{72C}{12C} = 6\ \text{V}$$
Solution by Sreeraj P, M.Sc Physics