1. Capacitors

2. What are they? A device that stores electrical potential energy by storing charge. How is that useful? Capacitors are used when a lot of energy is needed quickly (brief burst of power) What does a capacitor consist of? Any two conducting objects separated by a vacuum or other type of insulating material.

3. Capacitance The ratio of the magnitude of the charge Q on either conductor to the magnitude of the potential difference V between the conductors. The Farad is named after the English physicist/chemist Michael Faraday who had many valuable contributions in the field of electromagnetism.

4. Parallel Plate Capacitors Capacitor with two parallel plates of area A and separation distance d. The electric field between the plates is uniform. The capacitance of a parallel plate capacitor is: Notice: Capacitance of a parallel plate capacitor is not dependent on the charge of the capacitor, but rather on the dimensions of the plates and the separation.

5. Parallel Plate Capacitor A parallel plate capacitor has a capacitance of 1.0 F, and the plates are 1 mm apart. What is the area of the plates? This is about 10 km per side…bigger than Manhattan!! Common values for capacitance are microfarads (1 μ F = 10 -6 F) and picofarads (1 pF = 10 -12 F)

6. Capacitor Energy The oppositely charged plates of a capacitor are comparable to a stretched spring or an object lifted to a higher gravitational potential energy. The energy stored in a capacitor is: