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2nd year - Test #4 > AC theory, Level 1- 4,5,6,7 > Flashcards

AC theory, Level 1- 4,5,6,7 Flashcards

1
Q

The physical structure of a(n) ? consists of two conducting surfaces separated by an insulating material.

A

capacitor

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2
Q

A(n) ? will not hold its charge indefinitely.

A

capacitor

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3
Q

? is the letter designation for capacitance.

A

C

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4
Q

C is the letter designated for?

A

capacitance.

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5
Q

One farad ? a practical unit of capacitance.

A

Is not

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6
Q

The unit of capacitance is the farad, abbreviated ? .

A

F

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7
Q

F is the abbreviation for?

A

The unit of capacitance is the farad

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8
Q

The unit of capacitance is the ?

A

farad

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9
Q

When a capacitor of one farad is connected to a source of one volt, its charge is one ?

A

coulomb

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10
Q

One microfarad in decimal form is ? and may be abbreviated ?

A

0.000001 F / 1 µF

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11
Q

A picofarad is also called a?

A

micromicrofarad and may be abbreviated µµF.

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12
Q

a micromicrofarad and may be abbreviated µµF is also called a?

A

Picofarad

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13
Q

One picofarad is one farad times ? .

A

10−12

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14
Q

factors that determine the capacitance of a capacitor.

A

Area of the plates (conducting surfaces)

Distance between the plates

The type of dielectric used (insulating material)

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15
Q

When a DC voltage source is connected to a capacitor, electrons will be moved from the plate connected to the ? and deposited on the plate connected to the ? pole. This will continue until the voltage across the capacitor equals the voltage source.

A

positive / negative

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16
Q

Current can flow only during the period of time that a capacitor is ? .

A

charging

discharging

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17
Q

The term ? refers to the force holding an electrical charge across a capacitor’s plates.

A

electrostatic

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18
Q

The ? field is formed when electrons are removed from one plate and deposited on the other.

A

electrostatic

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19
Q

Electrons ? flow through a capacitor. The dielectric between the plates prevents the electrons from flowing through the capacitor; the electrons flow from one conductive plate to the other conductive plate through the circuitry connected to the capacitor’s two terminals.

A

do not

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20
Q

If a capacitor is subjected to a voltage in excess of that for which it is designed, the electron flow may puncture the insulation, causing an arc-through, which destroys the ? and, therefore, the capacitor.

A

dielectric

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21
Q

An AC ammeter indicates a steady current when it is connected ?

A

in series with a capacitor across an AC source.

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22
Q

Current ? flow through a capacitor, but it ? flow from one conductive plate to the other conductive plate each half cycle. The meter indicates a steady current while the capacitor’s dielectric blocks electrons from flowing across the dielectric and actually flowing through the capacitor.

A

-cannot
-does

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23
Q

In a capacitive circuit, the current will ? the voltage by ? .

A

lead / 90°

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24
Q

he type of dielectric is a factor in determining the amount of ?

A

capacitance a capacitor will have.

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25
Q

A capacitor has the same area of plates and the same distance between the plates. The capacitance will be ? if air is used instead of insulating oil.

A

lower

26
Q

A time constant is the amount of time required to charge a capacitor to ? of the amount left to reach its full charge.

A

63.2%

27
Q

How many time constants are required to charge a capacitor to a level where it is considered to be fully charged?

A

5

28
Q

How many time constants for a capacitor to fully discharge?

A

5

29
Q

When a capacitor is connected in a circuit with a resistor, the amount of time needed to charge the capacitor is determined by the ? .

A

RC time constant

30
Q

study questions 23-25 Lesson 4

A

study questions 23-25 Lesson 4

31
Q

the proper safety rule(s) for working on circuits containing capacitance?

A

Be sure to discharge the circuit capacitance after the circuit is turned off.

Observe polarity marks when connecting capacitors to the circuit.

Be sure the capacitor’s voltage rating is greater than the peak voltage present in the circuit.

32
Q

what job can a capacitor perform in electrical work?

A

Produce large current pulses

Timing circuits

Power factor correction

33
Q

A capacitor consists of two conductors, usually referred to as plates separated by an insulator called the ? .

A

dielectric

34
Q

What physical factor determines the amount of capacitance?

A

Area of the plates

Distance between the plates

Type of dielectric

35
Q

The unit of capacitance is the ? and is symbolized by the letter ? .

A

farad / F

36
Q

A capacitor has the capacitance of one ? when a change of one volt across its plates results in the movement of one coulomb of electrons.

A

farad

37
Q

a capacitor that has a high level of current flow through its insulating material would be considered to have?

A

a weak (or leaky) dielectric

38
Q

current does not flow through a capacitor, but when connected to an ? , current appears to flow through a capacitor

A

alternating voltage supply

39
Q

The flow of electrons through the insulating material of a capacitor is called ? .

A

leakage

40
Q

? charge is the term used to describe the stationary charge stored in a capacitor.

A

electrostatic

41
Q

If the electrical stress across a capacitor is excessive, it will be destroyed. Therefore, the ? rating of capacitors should never be exceeded.

A

voltage

42
Q

A 120-VAC source is applied to a capacitor. The ? rating on the capacitor would have to be a minimum of 170 volts DCWV.

A

voltage

43
Q

Air has a ? constant of 1.

A

dielectric

44
Q

The dielectric in the reference text table with the ? constant is ceramic with a dielectric constant of up to 7,500.

A

highest

45
Q

When the dielectric of a capacitor is broken down, excessive ? will flow through the dielectric, shorting it.

A

current

46
Q

? capacitors can be used in either AC or DC circuits.

A

Non-polarized

47
Q

? capacitors are often used in motor circuits.

A

Oil-filled non-polarized

48
Q

Capacitors ? at an exponential rate.

A

I. charge
II. discharge

49
Q

When a graph is used to represent the rate-of-charge of a capacitor, it is broken down into ? time constants.

A

5

50
Q

During each time constant, the curve will see a change equal to ? of the amount of voltage left to reach the fully charged state.

A

63.2%

51
Q

After 5 times constants, a capacitor reaches over ? of the source voltage

A

99%

52
Q

applying reverse polarity to polarized capacitors can cause ?

A

dielectric breakdown and excessive current flow through the capacitator

53
Q

on polarized capacitators, one terminal must be identified as?

A

positive or negative

54
Q

The length of one time constant is dependent on the ? of the capacitor and the resistance in series with the capacitor.

A

farad rating

55
Q

formula to find a capacitors time constant.

A

T = R * C

56
Q

T = R * C is the formula for ?

A

to find capacitors time constant

57
Q

If an oil-filled capacitor has a terminal with an identification mark, this mark indicates that the terminal is connected to the plate that is located ? the outer metal container or can.

A

nearer to

58
Q

Electrolytic capacitors are the ? type.

A

polarized

59
Q

Capacitors often have their farad value and ? rating printed on them.

A

voltage

60
Q
A

2nd year - Test #4 (3 decks)

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