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A capacitor is a device that stores electrical energy in an electric field. It is a passive electronic component with two terminals.
A capacitor is similar to a toilet in several ways. The energy of water to the toilet ((Current and Voltage) per time) is insufficient (high resistance) to evacuate the bowl (Load Resistor), therefore the energy of water is stored in the tank. Until the time it is needed. The water is then released very quickly (low resistance and high current), thus evacuating the bowl. The switch at the bottom of the tank then allows water to flow into the tank, replenishing the water, until the switch (the handle) to release water is tripped.
Physical Characteristics of Capacitors
Physical Characteristics of Capacitors
Where:
A = Surface area of Conductive Plates (m2 )
d = distance separating the two plates (m)
ε = dielectric permittivity (F/m)
One farad can be described as the capacitance which stores a one-coulomb charge across a potential difference of one volt. (C/V)
Standard Units of Capacitance
Standard Units of Capacitance
Microfarad (μF) 1μF = 1/1,000,000 = 0.000001 = 10-6 F
Nanofarad (nF) 1nF = 1/1,000,000,000 = 0.000000001 = 10-9 F
Picofarad (pF) 1pF = 1/1,000,000,000,000 = 0.000000000001 = 10-12 F
The flow of electrons is counter to that of conventional current. Adding additional electrons to the negative plate becomes more difficult over time, hence the decreasing slope of the charge v. time graph.
Discharging the capacitor is essentially the opposite of charging, where the excess electrons are allowed to return the positive terminal while passing through a resistor (load).
Capacitance Background and Calculations
Capacitance Background and Calculations
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