Unit 20: Capacitors

The three factors that determine the capacitance of a capacitor are

1. The surface area of the plates 2. The distance between the plates. 3. The type of dielectric used.

A capacitor has a capacitance if ____ farad when a charge of ____ volt across its plates results in a movement of 1 _____

1/1/Coulomb

Capacitors connected in parallel

C1+C2+C3=CT

Capacitors connected in series

CT= 1/(1/C1)+(1/C2)+(1/C3)

Variable capacitors

Contain a set of movable plates and stationary plates

The rating of the dielectric material is called _________

Dielectric constant

The capacitors energy is stored in the __________

Dielectric material

Attraction causes electron orbit to stretch. Stretching of atoms of the dielectric is called _________

Dielectric stress

If a ______ capacitor connection become reversed it will not reform and be destroyed

Dry-type electrolytic

Polarized capacitors are

Electrolytic capacitors / sensitive to polarity connection (DC Capacitors)

A capacitor stores energy in an ________

Electrostatic field

Capacitors charge and discharge at an __________rate

Exponential

The basic unit of capacitance is the _________ and symbolized by the letter ___

Farad/F

The curve is divided into ____________. Each one changes by____

Five time constants/63.2%

A dry- type electrolytic capacitors has a advantage of being

Leak proof

Current flow through the dielectric is called ___________

Leakage current

Capacitors are generally rated at _______

Microfarads, nanofarads, or picofarads

Nonpolarized capacitors are

Not sensitive to polarity connection (AC capacitor)

Large AC oil filled caps can be tested for shorts with a ______ and capacitance. The dielectric strength can be tested with a ______

Ohmmeter / HIPOT

Capacitors are used for __________

Power factor correction, control frequency

Leakage current in ___________ to the ___________ of the dielectric and charge across the plate.

Proportional/resistance

When a capacitor is connected in a circuit with a resistor, the amount of time needed to charge the capacitor is _________

RC time constant (T=RxC)

Small capacitors are tested for _______ with a _____. To test for leakage apply ______ and connect to _____ and expect_____

Shorts / ohmmeter. DC / micrometer / zero current flow

A capacitor is constructed by

Sperating two metal plates by insulating material called dielectric

The greater the _______________ of the plates, the more capacitance a capacitor will have

Surface area

__________ indicates the amount of capacitance change with temp.

Temperature coefficients

Current can only flow when

The capacitor is charging or discharging

Capacitors are devices that oppose a change in

Voltage

If polarity of a ______ capacitor becomes reversed, the capacitor becomes shorted but if corrected can be resotred

Wet-type capacitor

Capacitors have the ability to supply almost ____ amount of current. capacitors have enough energy to cause _____

infinite, a persons heart to fibrillate

The greater the ______ the more capacitance a capacitor will have

surface area of the plates