An air-filled capacitor carries enough charge to store $6.00 \mathrm {~mJ}$ of potential energy. It is then accidentally filled with water in such a way as not to discharge its plates. How much energy does it continue to store after it is filled? The dielectric constant for water is 78 and for air it is 1.0006.

Question

Quizplus · Accepted Answer

When a capacitor is filled with a dielectric, the energy stored is reduced by a factor equal to the dielectric constant. The energy stored with water is $ \frac{6.00 \, \text{mJ}}{78} \approx 0.077 \, \text{mJ} $.

An Air-Filled Capacitor Carries Enough Charge to Store 6.00 mJ6.00 \mathrm {~mJ}6.00 mJ

An Air-Filled Capacitor Carries Enough Charge to Store $6.00 \mathrm {~mJ}$