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Low Voltage > Test 11 > Flashcards

Test 11 Flashcards

1
Q

The ________ prevents flow of electrons through a capacitor

A

Dielectric

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2
Q

Why does the smallest capacitor in a series circuit have the largest voltage drop?

A

It charges fastest

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3
Q

Assume 2 unequal capacitors are connected across a voltage source which will have the larger voltage across it?

A

The smaller capacitor

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4
Q

4 capacitor types

A

Variable
Fixed
Polarized
Non polarized

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5
Q

Fixed capacitor

A

Capacitance determined by manufacture

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6
Q

Define capacitance

A

Capacity of a circuit or circuit component to store electrical charge

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7
Q

Capacitance is measured in

A

Farads: micro farads or pico farads

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8
Q

Capacitors are always labeled in __________ unless stated otherwise

A

Pico

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9
Q

For a dc circuit with a series resistor, capacitor and switch when is the current at its maximum

A

Right after switch is closed

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10
Q

Ceramic capacitor

A

Non polarized
Small size
High capacitance

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11
Q

Capacitors build voltage to ________ circuit applied voltage

A

Oppose

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12
Q

Variable capacitor

A

Plate area can be adjusted

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13
Q

What precautions are necessary when using a polarized capacitor

A

Check polarity and voltage rating

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14
Q

The dielectric is a ___________ material

A

Insulating

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15
Q

4 main types of fixed capacitors

A

Mica
Ceramic
Electrolytic
Plastic film

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16
Q

When a capacitor is charging does current flow through the dielectric

A

No

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17
Q

Working voltage

A

The maximum sustained DC voltage a capacitor can withstand

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18
Q

What is relative permeability

A

Effectiveness of a given dielectric to that of air

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19
Q

Mica capacitor

A

Small size with high working voltage

20
Q

After the first time constant how charged is a capacitor

A

63 percent

21
Q

What is an electrolyte

A

A conductive material in which charge movement is by ions

22
Q

For constant dc a capacitor is equivalent to an _________ .

A

Open circuit

23
Q

What does the band on one end of a plastic film capacitor indicate

A

The outside foil

24
Q

How do you find capacitance in parallel

A

Sum all capacitors

25
Q

C

A

Capacitance in farads F

26
Q

Capacitance is

A

The ability to store voltage

27
Q

Q

A

Charge in coulombs

28
Q

When the plate area of a capacitor is increased capacitance ________.

A

Increases

29
Q

Capacitance is directly proportional to the _________ and _______

A

Relative dielectric constant and plate area

30
Q

Coulombs equation

A

Q = C X V

31
Q

What type of dielectric is in a electrolytic capacitor

A

An extremely thin layer of oxide

32
Q

Plastic film capacitor

A

Non polarized with a large plate area

Small size with high capacitance

33
Q

Capacitance ____________ voltage

A

Opposes

34
Q

Electrolytic capacitor

A

Very high capacitance they are polarized

35
Q

What are 3 factors that determine capacitance of a capacitor

A

Area of the plates
Separation of the plates
Dielectric

36
Q

As spacing between plates increases capacitance _______ and voltage _________

A

Decreases

Increases

37
Q

In a RC circuit current _______ voltage by ______ degrees

A

Leads 90

38
Q

Non polarized capacitor

A

Used in AC and dc without regard to electrical polarity

39
Q

Capacitors and current:

Current ________ voltage by _______ degrees

A

Leads

90

40
Q

Polarized capacitor

A

Definite positive and negative connection points for dc circuits

41
Q

Relative permeability of:

A 
Air 1
Teflon 2
Paper 2.5
Oil 4
Mica 5
Glass 7.5
Aluminum oxide 10
Ceramic 1200
42
Q

Time constant equation

A

T = r x c

43
Q

What are two types of electrolytic capacitors

A

Aluminum and tantalum

44
Q

WV is?

A

Working voltage

45
Q

How is a charge stored in a capacitor?

A

Electrostatic field

46
Q

Capacitance is inversely proportional to __________

A

distance between the plates

47
Q

How do you find capacitance in series

A

Reciprocal equation

Low Voltage (9 decks)

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