# Capacitance Formula

## Capacitance Formula

A capacitor is a commonly known electrical device. Also, after reading this article, you will be able to define capacitance, use the capacitance formula, and answer capacitance-related questions. Capacitor and capacitance are connected since capacitance is merely the capacitor’s ability to store charge. Capacitors are critical components of electronic circuits that store electrical energy in the form of an electric charge. They are often employed in a variety of applications, including power supply, filtering circuits, timing circuits, and coupling circuits. A capacitor’s capacity to store electrical energy is defined by its capacitance, which is a measure of the amount of charge that can be stored per unit of applied voltage. Understanding the foundations of capacitors and capacitance is vital for anybody working with electrical circuits or interested in electronics.

In this post, we will learn about capacitors, how they work, capacitance, and others.

## What is Capacitance?

The general description of capacitance for any electric equipment is its ability to store electric energy in the form of an electric charge. Capacitors are devices that store electrical energy in the form of an electric charge. There are several varieties of capacitors used in electric circuits; they come in a variety of forms and sizes and are utilised based on the needs of the circuit. A capacitor is typically constructed by conducting to plates of conductor and connecting them.

Inserting dielectric material between capacitors enhances their charge-holding capacity exponentially. The dielectric substance prevents electricity from passing through while increasing the strength of the capacitor. Generally, all insulators act as dielectric materials.

The formula to calculate the capacitance of any material,

C = Q/V

It is measured in Farad. The dimensions of the Capacitance is,

F = kg-1m-2s4A2 = [M-1L-2A2T4]

## Capacitance Defination

A capacitor is a two-terminal electronic device capable of storing energy. A capacitor is made up of two electric conductors that are formed like plates and are linked to separate materials. The space between them is filled with a dielectric substance, which boosts the capacitor’s ability to retain electric charge. Capacitance refers to a capacitor’s capacity to hold electrical charge.

A capacitor is capable of storing both electric charge and electric energy. So what’s the difference between a capacitor and an electric battery? As a battery, it also stores electric energy. So the primary difference between a battery and an electric charge is that a battery stores electric energy and gradually releases it over time, whereas a capacitor practically instantly releases all of its stored energy. A capacitor, often known as a condenser, is a crucial component of a typical electric circuit. We regularly utilised capacitors to block direct current (dc) while allowing alternating current (ac) to flow in any electrical circuit. The capacitor is a device that stores electrical energy in the form of electric charge. It is made up of two plates that are parallel to each other and have opposing charges. Positive plates gather charges, whereas negative plates collect an equal number of opposing charges. When the circuit is turned on, the capacitor stores energy as an electric charge between its plates.

Switching off the circuit does not cause the capacitor to lose its charge, therefore it retains the electric energy as an electric charge between its plates. The capacitance or strength of a capacitor is measured in farads (F), which are named after the renowned English physicist Michael Faraday. A farad is an enormous unit of capacitance. Most capacitors are measured in microfarads (µF), picofarads (pF), and so on. Supercapacitors are specifically constructed capacitors with capacitances in the thousands of farads.

## How Do I Increase the Capacitance of a Capacitor?

The capacitance of any capacitor may be raised using the technique described below:

By lowering the spacing between the capacitor’s two plates.
By increasing the Area of the plates of the capacitor.
Insert an appropriate dielectric material between the capacitor’s plates.

## Unit of Capacitance

The SI unit to measure the capacitance of the material is Farad. It is denoted by the letter F and is a bigger unit of capacitance, so is not widely used.

### Smaller Units of Capacitance

The more common units of capacitance are,

• Microfarad and its value is, 1 µF = 10–6 F
• Nano farad and its value is,1 nF = 10–9 F
• Picofarad and its value is,1 pF = 10–12 F

## Capacitance Formula

We know that the capacity of any material to hold electric energy in the form of an electric charge is called capacitance. And we can compute the capacitance of any object by taking the ratio of the charge a conductor holds and the potential difference across the conductor. We know that the charge held by a capacitor is directly proportional to the voltage across the end of the capacitor, i.e.

Q ∝ V

Removing the sign of proportionality, and adding C as the constant of proportionality

Q = CV

C = Q / V…(i)

Here, this constant of proportionality is called the Capacitance of the Capacitor. Equation 1 is the required formula for calculating the capacitance of the capacitor and we can say that the capacitance of any capacitor is the ratio of the charge stored by the conductor to the voltage across the conductor.

Another formula for calculating the capacitance of a capacitor is,

C = εA / d

where
C is the Capacitance of the Capacitor
ε is the Permittivity of the medium Between the Plates
A is the Area of the Plates
d is the distance Between the Plates

## Solved Example on Capacitance Formula

Example 1: A capacitor is completely charged with 650 nC by a voltage source that has 275 V. The initial air gap of the capacitor was 7 mm. What is the stored energy if the air gap is now 3 mm?

Solution: Given,

• Charge on Capacitor (Q) = 650 nC = 650 × 10-9 V
• Voltage of Source (V) = 275 V
• Initial Air Gap (d1) = 7 mm
• Final Air Gap (d2) = 3 mm

Using Capacitance Formula

C = (650 × 10-9) / 275

C1 = 2.36 × 10−9 F

Gap between the plates changed from 7 mm to 3 mm

C1d1 = C2d2

C2 = C1d1/d1

C2 = [(2.36 × 10−9) (7 × 10−3)] / (3 × 10−3)

=  5.5 × 10−9 F

Energy stored in the Capacitor is given by the formula,

E = (1/2) C2V2

E = 5.5×10−9× (275)2

= 207.9 μ J

Thus, the enegry stored in the capacitor is 207.9 μ J

## FAQs (Frequently Asked Questions)

### 1. What is a Capacitor?

A capacitor is an electrical device that is used to store electric energy in the form of electric charge. It is one of the basic components of electric circuits.

### 2. What is Capacitance Formula?

The formula to calculate the capacitance of any material is,

C = Q / V

where
C is the Capacitance measured in farads (F)
Q is the Charge measured in Coulombs (C)
V is the Potential Difference measured in volts (V)

### 3. What is Capacitance Unit?

The SI unit to measure the capacitance of any material is Farad, denoted as F. The farad is a very big unit of capacitor, so the most common unit of capacitance is μF (10-6 F), or nF(10-9F).