Capacitor construction, Physics

Capacitor construction:

FIXED CAPACITORS

Fixed capacitors usually consist of sheets of metal foil between which is sandwiched the dielectric, or alternatively the metal, such as aluminium, is deposited onto both sides of the dielectric. The characteristics and quality of the capacitor depends mainly on the dielectric, which may be paper, chemically impregnated paper, plastics mica or ceramic.

VARIABLE CAPACITORS

Variable capacitors are usually meter plates with air as the dielectric. The variation is achieved by varying the area of overlap of the plates.
Preset capacitors may use air, mica or ceramics as the dielectric.

ELECTROLYTIC CAPACITORS

Electrolytic capacitors use the metal oxide as the dielectric which is formed directly on the metal plates. High values of capacitance can be achieved here with small physical size. Most electrolytic capacitors must be connected into circuit with the correct polarity or damage (possibly including explosion) may result.

SAFE WORKING VOLTAGE

The safe working voltage is the maximum d.c. voltage that can safely be applied to a capacitor without causing the dielectric to break down.

When breakdown occurs, the electric field is strong enough to ‘tear' electrons free from their orbits. A current then flows with the production of a large amount of heat. The dielectric is commonly burned through rendering the capacitor unserviceable.
Higher voltage require thicker dielectrics, but this reduces capacitance. Thus, a given value of capacitance requires a larger capacitor (greater plate area ‘a') for greater voltage working.

 

Posted Date: 9/13/2012 4:22:01 AM | Location : United States







Related Discussions:- Capacitor construction, Assignment Help, Ask Question on Capacitor construction, Get Answer, Expert's Help, Capacitor construction Discussions

Write discussion on Capacitor construction
Your posts are moderated
Related Questions
Q. What are coherent sources? Two sources are alleged to be coherent if they emit light waves of the same wave length and start with same phase or have a constant phase differ

Principles of radiation therapy: The basic principle of radiation therapy is to maximize damage to the tumor while minimizing damage to the normal tissue.Factors that determin

The recombination procedure is represented with returning the electron from the CB where it is free into a hole in the VB where it is in a bond. The excess energy of the electron

Q. A managing wire of length 2m has a diameter of 0.4 mm with a resistance of 70 ohm. Find its resistivity. ρ = ( P X πr 2 ) / L                   = ( 70 X 22 X 2 X 10 -4 X 2

An electron in the hydrogen atom loses 3.02 eV as it falls to energy level E 2 . From which energy level did the atom fall?

A pure semiconductor is known as intrinsic semiconductor. It has thermally formed current carriers (i)  They have four electrons in the outer part of orbit of atom and atoms are

Q. Explain the Law of Machines? Answer:- Machines which are utilized to lift a load are governed by the Law of machines which states that the effort to be applied on the m

What do you understand by "Absorption coefficient"? which is a better absorber of sound, glass or fibre glass?