Unit 3. Capacitors. Vocabulary

Unit 3. Capacitors

Vocabulary

advantage                             преимущество

besides                                  кроме того

capacitor                               конденсатор

disadvantage                        недостаток

distance                                расстояние

fixed capacitor                     конденсатор постоянной емкости

for this reason                      по этой причине

to move                                двигать(ся), перемещать(ся)

open                                      обрыв, разрыв

part                                       часть

plate                                      анод

to prevent                             предотвращать

reason                                   причина

to smooth                             сглаживать

to store charge                      накапливать заряд

variable capacitor                конденсатор переменной емкости

 

Text

A capacitor is one of the main elements of a circuit. It stores electric

charge. A capacitor stores electric energy provided that a voltage source is applied to it. Capacitors are used to smooth varying DC supplies by acting as a reservoir of charge. They are also used in filter circuits because ca- pacitors easily pass AC signals but they block DC signals.

Capacitance is a measure of a capacitor’s ability to store charge.

Large capacitance means that more charge can be stored. Capacitance is measured in farads.

The main parts of a capacitor are metal plates and insulators. The function of insulators is to isolate the metal plates and in this way to prevent a short.

Two common types of capacitors in use

nowadays are a fixed capacitor and a variable one. The plates of a fixed capacitor cannot be moved; for this reason its capacitance does not change. The plates of a variable capacitor move; its capacitance changes. The greater the distance between the plates, the less is the capacitance of a ca- pacitor. Variable capacitors are commonly used by radiomen; their func- tion is to vary the frequency in the circuit. Fixed capacitors are used in tel-

ephone and radio work.

Fixed capacitors have insulators pro- duced of paper, ceramics and other materials; variable capacitors have air insulators. Paper capacitors are commonly used in radio and electronics; their advantage is their high ca- pacitance, it may be higher than 1,000 pico- farad.

Besides, electrolyte capacitors are highly in use. They also have a very high capacitance; it varies from 0.5 to 2,000 microfarad. Their disad- vantage is that they change their capacitance when the temperature chang- es. They can operate without a change only at temperatures not lower than

-40° C.

Common troubles in capacitors are an open and a short. A capacitor stops operating and does not store energy in case it has a trouble. A capaci- tor with a trouble should be substituted by a new one.