Two identical parallel-plate capacitors, each with capacitance 10.0 μF, are charged to potential difference 50.0 V and then disconnected from the battery. They are then connected to each other in parallel with plates of like sign connected. Finally, the plate separation in one of the capacitors is doubled. (a) Find the total energy of the system of two capacitors before the plate separation is doubled. (b) Find the potential difference across each capacitor after the plate separation is doubled. (c) Find the total energy of the system after the plate separation is doubled. (d) Reconcile the difference in the answers to parts (a) and (c) with the law of conservation of energy.

A capacitor consists of two parallel plates, each with an area of 9.10*10-4 m2 and separated by a distance of 2.70*10-3 m .  If a 5.80 V potential difference is applied to these plates, calculate a) the capacitance, and b) the charge on one plate.

A model of a red blood cell portrays the cell as a spherical capacitor, a positively charged liquid sphere of surface area A separated from the surrounding negatively charged fluid by a membrane of thickness t. Tiny electrodes introduced into the interior of the cell show a potential difference of 100 mV across the membrane. The membrane's thickness is estimated to be 96 nm and has a dielectric constant of 5.00.  (a) If an average red blood cell has a mass of 1.10 ✕ 10−12 kg, estimate the volume of the cell and thus find its surface area. The density of blood is 1,100 kg/m3. (Assume the volume of blood due to components other than red blood cells is negligible.) volume     m3 surface area     m2 (b) Estimate the capacitance of the cell by assuming the membrane surfaces act as parallel plates. (c) Calculate the charge on the surface of the membrane. How many electronic charges does the surface charge represent?

The plates of a parallel-plate capacitor are charged to a potential difference of 35.0 V. If the capacitance is 49.0 µF, calculate the following. (a) the energy stored in the capacitor (b) the magnitude of charge stored on each plate of the capacitor