Electronics

Question 1

How many electrons are in the outer shell?

Answer 1

8

Question 2

What are covalent bonds?

Answer 2

Chemical bond of sharing electron pairs between atoms

Question 3

What are valence electrons?

Answer 3

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

Question 4

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

Answer 4

1-3

Question 5

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

Answer 5

5-8

Question 6

How many valence electrons do semi conductors have?

Answer 6

4

Question 7

What is doping?

Answer 7

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

Question 8

What is an N type seni conductor?

Answer 8

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.

Question 9

What is a P type semi conductor?

Answer 9

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

Question 10

What is negative temperature coefficient

Answer 10

As temperature increases, resistance decreases, current increases.

Question 11

What is built into diodes to dissipate heat?

Answer 11

Heat sink fans

Question 12

What is a diode made of?

Answer 12

A P type and an N type semiconductor

Question 13

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

Answer 13

Anode, positive.

Question 14

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

Answer 14

Cathode, negative

Question 15

Voltage drop across reverse and forward bias diodes

Answer 15

Reverse: will read source, acts as an open

Forward: silicon: 0.7V, Germanium: 0.3V

Question 16

Resistance of reverse and forward bias diodes

Answer 16

Reverse: infinite, will not conduct

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

Question 17

What type of switch is a diode?

Answer 17

Solid state switch

Question 18

When does breakdown voltage occur?

Answer 18

When PIV is surpassed

Question 19

What is PIV?

Answer 19

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)

Question 20

Forward Current Rating:

Answer 20

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

Question 21

Zener diodes conduct in reverse or forward bias?

Answer 21

Forward.

Question 22

Why are Zener diodes used as voltage regulators?

Answer 22

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

Question 23

What are zener diodes rated in?

Answer 23

Watts

Question 24

Term for turning AC into DC

Answer 24

Rectifier

Question 25

Term for turning DC into AC

Answer 25

Inverter

Question 26

Formula for finding Eavg on a half wave circuit

Answer 26

Epeak / pi

Question 27

Formula for finding Eavg on a full wave

Answer 27

Epeak • 2 / pi

Question 28

Formula for finding Iavg on half wave

Answer 28

Ipeak / pi

Question 29

Formula for finding Iavg on full wave

Answer 29

Ipeak • 2 / pi

Question 30

Formula for finding power on a half wave

Answer 30

Epeak • Ipeak / 4 Or ERMS • IRMS / 2

Question 31

Formula for finding power on a full wave

Answer 31

Epeak • Ipeak / 2 Or ERMS • IRMS

Question 32

What is a rectifier half wave?

Answer 32

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

Question 33

What amount of power is produced in a half wave?

Answer 33

Half the source power, half the waveform is blocked.

Question 34

Dc meters measure ______ values

Answer 34

Average

Question 35

AC meters measure ________ values

Answer 35

rMS

Question 36

What is a rectifier full wave?

Answer 36

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

Question 37

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

Answer 37

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

Question 38

Name two types of full wave rectifiers

Answer 38

Bridge, biphase

Question 39

In a bridge rectifier, load power =

Answer 39

Same power as source.

Question 40

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

Answer 40

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

Question 41

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

Answer 41

Short circuit.

Question 42

What is PIV on a biphase rectifier?

Answer 42

Peak of voltage across both coils.

Question 43

What is the purpose of capacitors for filtering?

Answer 43

To smooth out the pulses.

Question 44

What must the PIV be rated in a filtering circuit?

Answer 44

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

Question 45

How is a capacitor connected in a circuit?

Answer 45

In series with a diode.

Question 46

What does Max filtering mean?

Answer 46

DC avg = AC peak

Question 47

What are the bridge rectifier colour codes

Answer 47

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

Question 48

PIV in a half wave filtering circuit would be

Answer 48

2x the peak without filtering.

Question 49

What is DCWV in a biphase rectifier?

Answer 49

Peak voltage on one winding

Question 50

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

Answer 50

Increases

Question 51

Collector current in a PNP will decrease as base becomes less

Answer 51

Negative

Question 52

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

Answer 52

0.1V

Question 53

When a transistor is fully on the voltage across be is

Answer 53

0.7V

Question 54

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

Answer 54

Low

Question 55

The beta can range anywhere from ____ to _____

Answer 55

10 to 500

Question 56

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

Answer 56

The number of valence electrons

Question 57

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

Answer 57

N type: pentavalent P type: trivalent

Question 58

What is meant by forward bias?

Answer 58

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

Question 59

What is meant by reverse bias?

Answer 59

Connected polarity which will make diode block

Question 60

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

Answer 60

Forward bias: low resistance Reverse bias: high resistance

Question 61

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

Answer 61

Reverse bias diode in parallel

Question 62

Describe the valence shell of a P type

Answer 62

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

Question 63

Describe the valence shell of an N type

Answer 63

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

Question 64

What is the resistor colour code?

Answer 64

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

Question 65

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

Answer 65

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

Question 66

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

Answer 66

Peak of the source voltage

Question 67

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

Answer 67

0.1V

Question 68

What is the photodiode or LED current rating

Answer 68

10- 50 ma

Question 69

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

Answer 69

1.2 - 3.6 V