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I am sorting through some ceramic capacitors and reorganizing them. I came across a number of capacitors with "82" on them (at left), which I assume is 82pF, but they are physically larger than even my 0.1μF capacitors (at right).

Ceramic Caps

Does the large size of these capacitors relate to their voltage rating (or something else), or did I misinterpret the capacitance value?

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For a big capacitor the distance should be low and area should be high because capacitance is directly proportional to area of the plates and inversely proportional to the distance between the plates. But if the distance is too low, the dielectric will get punctured with voltage. So there must be a proper distance between the plates according to voltage; and for that distance, the area should be high as to get the required capacitance.

So in any capacitor, the size depends on voltage and its capacitance value because voltage rating is proportional to distance between plates and capacitance is proportional to area of the plates.

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The 82.pF caps looks to be around 300-400 Volts while the .1uF cap is probably 12-16 Volts.

Ceramic caps don't usually have a problem with power ratings outside of high power RF circuits where special metal cased caps are used where inductance of the wire leads is the main concern

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    \$\begingroup\$ I assume that, without any additional markings on the capacitor, there's no way to know the voltage rating for certain without its datasheet? (Not that I care, I just wondered if the voltage rating was what affected the package size.) \$\endgroup\$ – JYelton Aug 18 '13 at 1:31
  • \$\begingroup\$ @JYelton you can get pretty darn close. you know the area and the capacitance and ceramic dielectrics tend to have similar qualities. From those you can calculate the exact distance between the plates, look up the breakdown voltage of the dielectric at that thickness. \$\endgroup\$ – John Meacham Feb 1 '15 at 9:07
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Check this answer:

Maximum current and voltage of Small Ceramic Capacitors?

They are a standard, so most of them can manage almost the same voltage/current for the same capacitance value.

That is the reason there are power capacitors, electrolytics, ceramic and others. All of them depends on the usage you need.

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