what function does a capacitor carry out in a circuit?

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I am a professional electronics engineer. This is my answer. A capacitors primary function is to store electrical charge and therefor electrical energy. In a circuit this ability can perform certian functions.  In an a circuit with alternating current ( Ac) at low frequency ( 50 Hz) like a motor it is used to make a phase shift or time delay in the motors windings  to create a psuedo rotating magnetic field, which causes the motors shaft to rotate. simularly  a capacitor can introduce a phase shift that is opposite to that caused by an inductor in the same circuit ( windings around iron).. This is done to correct the overal power factor of the circuit  which reduces energy wasted in the supply system.
 In other applications at higher frequencies from audio to microwaves , the capacitor can be used to form filters and oscillators, again using its properties of energy storage and time delay . A combination of capacitor and inductor will form an ocillator because their energy storage capabilities are opposite in time in an AC circuit , like a ball bouncing. This oscilltor can be tuned to a precise frequency by the value of te capacitor. The capacitor can also be used in a similar way to filter out wanted or unwanted frequencies in a system.Example:;- to remove an otherwise audiable hum from the 50 hz mains frequency on you TV or to "Tune you radio to a wanted radio frequency say BBC Radio 1 in the uk
 In direct current circuits (DC) the capacitor is primarily used to stor energy  E = 1/2 C( V squared) where E is the Energy in Joules, C is the capacitance in Farads and V is the voltage  measred n the capacitors terminals.  Note how the engery stored rises rapidly as a function of the voltage. This is often the basis of capacitor based electronic ignition systems and also energy "harvesting" systems. Capacitors can have values from 1 farad or more at low voltage - down to 1 picofarad ( 10 to the minus 12) at very high voltage
 Typical  values used  are from 100,000 microfarad at 50 V down to 1 picofarad at several thousand volts. Capacitor values are primarily a function of voltage, whereas Inductor values are primarily a function of electric current.
 Capacitance and inductance are fundamental properties of nature and can be explained right down to the quantum level, - free space has properties of both inductance and capacitance, though nobody really understands why!
 Hope that helps!

Capacitance tolerance	5
Maximum voltage	450 Volts
Mounting type	Panel Mount
Product dimensions	41W x 71H millimetres
Manufacturer	sourcing map
Part number	a21011900ux0287
Item Weight	90 g
Manufacturer reference	a21011900ux0287
Batteries Required?	No

sourcing mapCBB60 Run Capacitor 16uF 450V AC Double Insert 50/60Hz Cylinder 72x40mm White for Air Compressor Water Pump Motor

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