# MiscEl: Capacitor calculations

 Back to MiscEl main page Write a message to author The basic formula to calculate capacitance is: Capacitance=dielectricConstant*area/distance, this formula has good accurancy, as long as the area is large compared to distance*distance.
Most calculations in this program is based on that formula.

### Geometries supported

• Capacity, used to calculate "charge" and "energy" for known capacitors.
• Area, your must calculate area, can be used for unsupported geometries.
• Square, two stacked square plates.
• Rectangle, two stacked rectangular plates.
• Circle, two stacked circular plates.
• Stack, a number of stacked rectangular plates.
• Roll, a roll with two conductive foils and two isolating foils.
• Tube/coax, two cylinders inside each other
• Sphere an sphere, two spheres inside each other
• Wire, a wire above a groundplane
• Wires, two wires close to each other, i.e. a cable

### Input values

Diameter of the core in the roll
 Capacity Capacitance of the capacitor to analyze Area Area between plates of a capacitor Side One of the sides in a square Width One of the sides of a rectangle Height The other side of a rectangle of high above a groundplane Diameter Diameter of a circular plate Plates Number of plates stacked Length Length of the foil used for a roll, a coax/tube or a wire Conductor thickess Thickness of the conductor in a roll Inner diameter Tube inner diameter Inner diameter of the large tube in a tube/coax Center diameter Outer diameter of the smaller tube/wire in a tube/coax Radius inner sphere Outer diameter of the smalle sphere Radius outher sphere Inner diameter of the large sphere Distance Distance center of between two wires Dielectric Select the dielectric used or select"User absolute" or "User relative" Permittivity Used when dielectric is "user ...", must be filled with relative or absolute permittivity Thickness Thickess of dielectric Applied voltage Voltage applied to capacitor, used to calculate some electric values for capacitor
Note: All measurement inputs, are in meters.

### Output values

 Total area The total area between the plates Capacity The actual capacitance Permittivity (abs)/(rel) The permittivity of the selected dielectric shown as both absolute and relative value Dielectric volume The volume of the dielectric Turns Number of turns on a roll Outer diameter Outer diameter of a roll Field The electric field in the dielectric Charge The charge on the capacitor Energy The energy in the capacitor Energy density Density of energi en dielectric Force The force the electric field applies to the plates

### Hints

• To enter a value in inch, use the calculating ability of the input field. i.e. 3 inch is entered as "3*inch". This constant comes from the Calculator const page (This does NOT work for the wire diameter field, it expects input in mm, not meter)
• Dielectric constant for glass is not included because it can vary between 4 and 15 (relative) depending on glass type