Capacitors
Just like the Resistor, the Capacitor, sometimes referred to as a Condenser, is a simple passive device that is used to store electricity. The capacitor is a component which has the ability or capacity to store energy in the form of an electrical charge producing a potential difference (Static Voltage) across its plates, much like a small rechargeable battery.
There are many different kinds of capacitors available from very small capacitor beads used in resonance circuits to large power factor correction capacitors, but they all do the same thing, they store charge.
In its basic form, a Capacitor consists of two or more parallel conductive (metal) plates which are not connected or touching each other, but are electrically separated either by air or by some form of a good insulating material such as waxed paper, mica, ceramic, plastic or some form of a liquid gel as used in electrolytic capacitors. The insulating layer between a capacitors plates is commonly called the Dielectric.
Due to this insulating layer, DC current can not flow through the capacitor as it blocks it allowing instead a voltage to be present across the plates in the form of an electrical charge.
The conductive metal plates of a capacitor can be either square, circular or rectangular, or they can be of a cylindrical or spherical shape with the general shape, size and construction of a parallel plate capacitor depending on its application and voltage rating.
When used in a direct current or DC circuit, a capacitor charges up to its supply voltage but blocks the flow of current through it because the dielectric of a capacitor is non-conductive and basically an insulator. However, when a capacitor is connected to an alternating current or AC circuit, the flow of the current appears to pass straight through the capacitor with little or no resistance.
There are two types of electrical charge, positive charge in the form of Protons and negative charge in the form of Electrons. When a DC voltage is placed across a capacitor, the positive (+ve) charge quickly accumulates on one plate while a corresponding negative (-ve) charge accumulates on the other plate. For every particle of +ve charge that arrives at one plate a charge of the same sign will depart from the -ve plate.
Then the plates remain charge neutral and a potential difference due to this charge is established between the two plates. Once the capacitor reaches its steady state condition an electrical current is unable to flow through the capacitor itself and around the circuit due to the insulating properties of the dielectric used to separate the plates.
The flow of electrons onto the plates is known as the capacitors Charging Current which continues to flow until the voltage across both plates (and hence the capacitor) is equal to the applied voltage Vc. At this point the capacitor is said to be fully charged with electrons. The strength or rate of this charging current is at its maximum value when the plates are fully discharged (initial condition) and slowly reduces in value to zero as the plates charge up to a potential difference across the capacitors plates equal to the source voltage.
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The amount of potential difference present across the capacitor depends upon how much charge was deposited onto the plates by the work being done by the source voltage and also by how much capacitance the capacitor has.
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1. The Resistor - . A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits. In electronic circuits, resistors are used to limit current flow, to adjust signal levels, bias active elements, and terminate transmission lines among other uses.
2. Insulating material - . The main energy-saving methods become insulating materials. The manufacturing technology of such products can insulate and maintain a temperature without harm to others. For events in isolation, you can save more than 40% of energy and to protect against corrosion of metal piping.
3. Insulating layer - . The layer provides the necessary thermal performance of the multilayered pipe structure.
4. parallel plate capacitor - . The simple type of capacitor is a flat capacitor with parallel plates, made of two parallel sheets of metal separated by an insulator (called the dielectric), and one of the plates is grounded.
5. The capacitor dielectric - . Commercially manufactured capacitors typically use a solid dielectric material with high permittivity as the intervening medium between the stored positive and negative charges.
6. Static Voltage - . Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points or the difference in electric potential energy per unit charge between two points.
7. Electrical charge - . Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.
8. Electric potential difference ( ) - is the difference in electric potential energy between two points per unit electric charge.
Rewrite each question in indirect speech.
1) What time does the film start, Peter? I asked Peter what time film started.
2) Do you watch television every evening, Chris? The interviewer asked hris if watched television every evening.
3) Why did you apply for the job? asked the sales manager. The sales manager asked why I had apply for the job.
4) Are you taking much money with you to France? My bank manager wanted to know if I was taking much money with me to France.
5) When will I know the results of the examination? Maria asked the examiner
when she would know the results of the examination.
6) Are you enjoying your flight? The flight attendant asked me if I was enjoying my flight.
7) How does the photocopier work? I asked the salesman how the photocopier worked.
8) Have you ever been to Japan, Paul? Sue asked Paul if he had ever been to Japan.
1. What is a capacitors and why is it needs?
2. What it consists of a capacitors?
3. What materials are used for insulating materials?
4. Which shape could be metal plates of capacitor?
5. What are the types of electrical charges and how do they work?
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6. What are the principles for capacitors work?
Summary
It is described in short about capacitors. Also, various types of capacitors are given. Text introduces basic structure and shapes of capacitor. Attention is drawn to ability to work at different currents. Working process of capacitor and electrons flows in it are investigated.
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2. .. . 2010
4. New Oxford American Dictionary, 3rd Edition. 2010 by Oxford University Press Inc., 350000
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