The plates of an empty parallel-plate capacitor of capacitance 5.0 pF are 2.0 mm apart. What is the area of each plate?
An air-filled (empty) parallel-plate capacitor is made from two square plates that are 25 cm on each side and 1.0 mm apart. The capacitor is connected to a 50-V battery and fully charged. It is then disconnected from the battery and its plates are pulled apart to a separation of 2.00 mm.
What is the capacitance of this new capacitor?
What is the charge on each plate?
What is the electrical field between the plates?
An anxious physicist worries that the two metal shelves of a wood frame bookcase might obtain a high voltage if charged by static electricity, perhaps produced by friction. The shelves have an area of 1.00 m2 and are separated by a distance of 0.200 m. A total charge of 2.00 nC is placed on the two shelves.
What is the capacitance of the shelves?
What is the potential difference across the shelves?
How much energy is stored in the electric field between the shelves?