By: Griffin Thomas

capacitor  A capacitor is an electrical device that stores energy. Most electrical devices have some capacitance either intentional or accidental  The energy is stored by maintaining a potential difference between two conductors.  The energy is stored in the electric field between the conductors  Any electrical device that creates electrical fields creates some capacitance  The geometry of the capacitor affects the amount of energy stored. Capacitors are rated by capacitance, C, which is the ability of a given capacitor to store charge.  A dielectric is a material that when used in a capacitor increases the efficiency of the capacitor  A capacitor is unlike a power supply (which also maintains an electrical potential between two points) in that it is limited by the fact that it can store only a finite amount of charge.

Capacitance Capacitance is the ratio of the magnitude of the charge in a capacitor to the magnitude of the potential difference in the capacitor  Capacitance is always a positive quantity  Capacitance is a measure of the ability of a device to store charge and electrical potential energy.  Units of capacitance:  1 Farad is a huge amount of capacitance.  Typical capacitors have values on the order of (picofarads) to 10-6 (microfarads)  Capacitance depends upon the geometric arrangement of the conductors (plates)

 If one ignores the fringing field then the field between the plates is uniform. The distance between the plates is d. The field lines are parallel The field lines are perpendicular to each plate  For an electric field between two parallel plates then: Vb −VA = −Ed  The minus sign indicates that plate B is at a lower potential than plate A,VB < VA.  Parallel plate capacitors are essential in physics

 The charge density for each plate is  E between conducting plates is  The potential between the plates is  Note that capacitance for a parallel plate capacitor is proportional to area and inversely proportional to d.

 After watching the video and learning more, Lets solve a problem together. Remember ( C = Q/V ) 1). Determine the amount of charge stored on either plate of capacitor (4x10^-6F) when connected across a 12 volt battery.  C = Capacitance  Q = Charge  V = Volts  Answer: Q = (48x10^-6C)  Give yourselves a pat on the back

 Definition: Having the property of transmitting electric force without conduction; insulating.  Dielectrics increase the maximum operating voltage of a capacitor. (Capacitance)  Dielectrics may increase the mechanical strength of a capacitor.  Example:  After introduction of the dielectric material, the preexisting field polarizes the dielectric.  Polarization of the dielectric establishes a field within the dielectric that opposes the external field causing the capacitance to increase thus strengthening the system. Invisible bonds man. Learn about ‘em.

 Now lets jump into a new segment of dielectrics. Lets find the area of the conductive plates. This is the formula:  Tip: Absolute permeability (dielectric) (e) = 8.85x10^-12 1). If the plate separation for a capacitor is 2.0x10^-3 m, determine the area of the plates if the capacitance is exactly 1 F.  Answer: 2.3x10^8 m^2

 Parallel series are circuits that conduct electricity from a power source. With capacitors involved they can get trickier.  I will explain this in the schematics.  Does anybody know how to make this look simpler?  Solution?

 By getting rid of all three capacitors you can make the same circuit by creating a single capacitor with the total amount of capacitance.  Now how do you calculate total capacitance with similar and non-similar values like so:  Here is the first equation equation: Note: this is only if there are 2 capacitors  Now here is the equation if there are more than 3 capacitors in a series:

 Lets solve the total capacitance together.  Hint: There are 3 capacitors.  You did it guys! Hooray! You beat the capacitance and dielectrics crash course! Bravo!