Electronics Flashcards

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1
Q

How many electrons are in the outer shell?

A

8

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2
Q

What are covalent bonds?

A

Chemical bond of sharing electron pairs between atoms

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3
Q

What are valence electrons?

A

Electrons in the outer shell that can be shared with other atoms to form covalent bonds

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4
Q

How many electrons do the best conductors have in their outer shell?

A

1-3

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5
Q

How many electrons do the best insulators have in their outer shell?

A

5-8

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6
Q

How many valence electrons do semi conductors have?

A

4

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7
Q

What is doping?

A

Process of adding small impurity to semiconductor to make N type or P type

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8
Q

What is an N type seni conductor?

A

Has a material with 5 valence electrons introduced to it, outer 4 valence electrons create covalent bond leaving one extra electron to move around freely. There is an excess of Negative electrons hence the N.

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9
Q

What is a P type semi conductor?

A

A material with 3 valence electrons is introduced to a semi conductor, the outer valence electrons create a covalent bond with the 3 valence electrons of the new material leaving one hole available. This makes this semi conductor more Positive, hence the P

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10
Q

What is negative temperature coefficient

A

As temperature increases, resistance decreases, current increases.

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11
Q

What is built into diodes to dissipate heat?

A

Heat sink fans

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12
Q

What is a diode made of?

A

A P type and an N type semiconductor

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13
Q

What is the name and polarity of the P type semi conductor?

A

Anode, positive.

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14
Q

What is the name and polarity of the N type semi conductor?

A

Cathode, negative

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15
Q

Voltage drop across reverse and forward bias diodes

A

Reverse: will read source, acts as an open

Forward: silicon: 0.7V, Germanium: 0.3V

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16
Q

Resistance of reverse and forward bias diodes

A

Reverse: infinite, will not conduct

Forward: zero, will conduct easily with very little voltage drop

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17
Q

What type of switch is a diode?

A

Solid state switch

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18
Q

When does breakdown voltage occur?

A

When PIV is surpassed

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19
Q

What is PIV?

A

Peak inverse voltage. Max voltage diode can safely block. If value is passed the diode will start to conduct very high current and destroy itself (breakdown voltage)

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20
Q

Forward Current Rating:

A

Max RMS current value that diode can safely handle without damage.

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21
Q

Zener diodes conduct in reverse or forward bias?

A

Forward.

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22
Q

Why are Zener diodes used as voltage regulators?

A

In reverse bias they are able to change their resistance to maintain constant voltage over a range of currents.

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23
Q

What are zener diodes rated in?

A

Watts

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24
Q

Term for turning AC into DC

A

Rectifier

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25
Q

Term for turning DC into AC

A

Inverter

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26
Q

Formula for finding Eavg on a half wave circuit

A

Epeak / pi

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27
Q

Formula for finding Eavg on a full wave

A

Epeak • 2 / pi

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28
Q

Formula for finding Iavg on half wave

A

Ipeak / pi

29
Q

Formula for finding Iavg on full wave

A

Ipeak • 2 / pi

30
Q

Formula for finding power on a half wave

A

Epeak • Ipeak / 4
Or
ERMS • IRMS / 2

31
Q

Formula for finding power on a full wave

A

Epeak • Ipeak / 2
Or
ERMS • IRMS

32
Q

What is a rectifier half wave?

A

Only one alternation is allowed through, diode blocks the other alternation.

33
Q

What amount of power is produced in a half wave?

A

Half the source power, half the waveform is blocked.

34
Q

Dc meters measure ______ values

A

Average

35
Q

AC meters measure ________ values

A

rMS

36
Q

What is a rectifier full wave?

A

Both alternations of the sine wave are allowed through, but the negative has turned to positive, both waves are always positive

37
Q

Which is more advantages, half or full wave? Why?

A

Full wave DC, both alternations are used, more power dissipated

38
Q

Name two types of full wave rectifiers

A

Bridge, biphase

39
Q

In a bridge rectifier, load power =

A

Same power as source.

40
Q

What would happen in a bridge rectifier if one of the diodes was open?

A

Would change from a full wave to a half wave because you would lose one of the pulses.

41
Q

What would happen in a bridge rectifier if one of the diodes was incorrect polarity?

A

Short circuit.

42
Q

What is PIV on a biphase rectifier?

A

Peak of voltage across both coils.

43
Q

What is the purpose of capacitors for filtering?

A

To smooth out the pulses.

44
Q

What must the PIV be rated in a filtering circuit?

A

2x the peak value, capacitor acts as source so there is no down in the waveform

45
Q

How is a capacitor connected in a circuit?

A

In series with a diode.

46
Q

What does Max filtering mean?

A

DC avg = AC peak

47
Q

What are the bridge rectifier colour codes

A

Red: positive output of load
Black: negative output of load
Yellow: ac input

48
Q

PIV in a half wave filtering circuit would be

A

2x the peak without filtering.

49
Q

What is DCWV in a biphase rectifier?

A

Peak voltage on one winding

50
Q

As the base of a NPN becomes more positive, the collector current _____

A

Increases

51
Q

Collector current in a PNP will decrease as base becomes less

A

Negative

52
Q

When a transistor is fully on, the voltage across ce is

A

0.1V

53
Q

When a transistor is fully on the voltage across be is

A

0.7V

54
Q

When a transistor is saturated, the impedence between ce is low or high?

A

Low

55
Q

The beta can range anywhere from ____ to _____

A

10 to 500

56
Q

What determines if an element is classified as conductor, insulator, or semiconductor?

A

The number of valence electrons

57
Q

What type of atoms are used for doping n type and p type semiconductors?

A

N type: pentavalent
P type: trivalent

58
Q

What is meant by forward bias?

A

Connected polarity which will allow diode to conduct. (Positive to anode, negative to cathode)

59
Q

What is meant by reverse bias?

A

Connected polarity which will make diode block

60
Q

What kind of resistance would you expect when checking a diode with an on meter?

A

Forward bias: low resistance
Reverse bias: high resistance

61
Q

What type of connection is a free wheeling diode made in?

A

Reverse bias diode in parallel

62
Q

Describe the valence shell of a P type

A

Covalent bonds with an atom with three electrons, leaving excess of one hole making it more positive

63
Q

Describe the valence shell of an N type

A

Covalent bonds with an atom with an excess of negative electrons, leaving one extra

64
Q

What is the resistor colour code?

A

Black = Black
Beer = Brown
Rots = Red
Our = Orange
Young = Yellow
Guts = Green
But = Blue
Vodka = Violet
Goes = Grey
Well = Well

65
Q

What is the tolerance of gold and silver on the resistor colour code?

A

Gold = 0.1 -/+ 5%
Silver = 0.01 +/- 10%

66
Q

The DCWV if a capacitor in a half wave circuit is _____

A

Peak of the source voltage

67
Q

When a rheostat is shorted, what is the voltage across Vce?

A

0.1V

68
Q

What is the photodiode or LED current rating

A

10- 50 ma

69
Q

What is the range of voltage for a forward biased LED photodiode

A

1.2 - 3.6 V