Capacitance is the measure of the amount of the electrical energy stored or separated for a given electrical potential .Capacitance may be defined as the ability of the body to hold electrical charge. You can easily calculate the capacitance of the conductors if you know the geometry of the conductors and the dielectric properties of the insulators between the conductors. This article on how to calculate capacitance will help you in calculating capacitance.
Capacitance is usually of two types, self capacitance and mutual capacitance. We generally use the term mutual capacitance and need to calculate it most of the times. You can calculate both these capacitance separately using different formulas.
Calculating capacitance
Formula for calculating capacitance is given as:
In the above formula,
- C is the capacitance
- The charges on plates is +Q and –Q
- V is the voltage between the plates
The unit of capacitance is “farad” and one farad is equal to coulomb per volt. Farad is the SI unit of capacitance. The unit for measuring charge on the plate is coulomb and the unit for measuring voltage between the plates is Volts.
Calculating mutual capacitance between parallel plate capacitors
Mutual capacitance is the capacitance between two adjacent conductors such as two plates of capacitors.
- We commonly use parallel plate capacitor for storing. Capacitance is found to be directly proportional to the surface area of the conductor and inversely proportional to the separation distance between the plates. When two plates are placed to form a conductor, the capacitor is called the parallel plate capacitor.
- If the area of the plates is A and the plates are separated by a distance d, then the capacitance of the parallel plate capacitor is given by the formula,
In the above formula,
- C is the capacitance
- Єr is the dielectric constant of the material that exists between the plates. This dielectric constant is usually 1 for vacuum.
- Є0 is the electric constant and the value for this electric constant is approximately 8.854 × 10-12 F/m
- A is the area of overlap of the two plates
- D is the distance between the plates or the separation between the plates
Self Capacitance
Self capacitance is the amount of electric charge that must be added to an isolated conductor so as to raise its electrical potential by one volt.
- The formula for calculating self capacitance of a hollow conducting sphere of radius R is given by the formula:
C = 4 π є0 R
In this formula,
- C and є0 are same as in the above formula
- The value for π is 3.141 or 22/7
- R is the radius of the sphere.
Practically we do not use the capacitors having the capacity on farad. The capacitance of the capacitors is generally in much more i.e. is in picofarad (pF), nanofarad (nF), microfarad (µF), millifarad (mF).
Capacitance has a lot of applications such as for safety alarms and on-off controls. Capacitance provides accurate measurement and is used in alarm points in most of the applications. Because they are inexpensive, they are gaining popularity on a large-scale in the manufacture of level tank alarm applications, reservoir observation and process control.
We need to measure the capacitance of the capacitors while using them in any of the applications, so it is worth knowing how to measure capacitance.
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I want to know calculation of mutual capacitance, inductance, receptacle & /R ratio