Capacitors

All electrical components have three properties

1. Resistance

2. Capacitance

3. Inductance.

In this topic we will discuss that what capacitance and capacitors is

A capacitor can be assumed as battery that can supply power to circuit for some instant . Battery is capable of generating new electrons form some chemical process s, how ever capacitor can only store electrons and than can use them

 

Construction

Generally a capacitor is made up of two conducting plates serrated by some dielectric . Dielectric is normally a non conducting material and is made up of normally glass air plastic or any other non-conducting material. Ddielectric dictates what kind of capacitor it is and for what it is best suited. Depending on the size and type of dielectric, some capacitors are better for high frequency uses, while some are better for high voltage applications.

Air	Often used in radio tuning circuits
Mylar	Most commonly used for timer circuits like clocks, alarms and counters
Glass	Good for high voltage applications
Ceramic	Used for high frequency purposes like antennas, X-ray and MRI machines

Symbol

 

Working

Charging Capacitor

The plate on the capacitor that attaches to the negative terminal of the battery accepts electrons that the battery is producing.

The plate on the capacitor that attaches to the positive terminal of the battery loses electrons to the battery.

 

Charged Capacitors

Once Capacitor is charged it will have same value as voltage in battery , at that point the potential difference across the circuit becomes zero and the current flow stops

Capacitors in Nature

Farad

A capacitor’s storage potential, or capacitance, is measured in units called farads. A 1-farad capacitor can store one coulomb of charge at 1 volt.l A 1-farad capacitor would typically be pretty big. It might be as big as a 1-liter soda bottle, .

Capacitance :

Capacitance is the ability of a capacitor to store a charge . It is the ratio of charge stored by a capacitor to the voltage across it.

C= Q/V

Example

Calculate the capacitance of a capacitor if it is connected to voltage source of 12 V and stores 24 µC charge

What is the voltage across Capacitor , when 16 µC is stored on it

Stray Capacitance

It is also called parasitic capacitance and it is unwanted capacitance that exist between different parts (wire) and other components of a wire . At higher frequency it becomes a very critical issues , specially while designing PCB for high frequency response

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