D6 DIODES

Question 1

The diode is a (linear/non-linear) device:

Answer 1

non-linear

Question 2

A diode in reverse breakdown can be used as a

Answer 2

voltage regulator or voltage reference

Question 3

As long as a Zener diode is in reverse breakdown, an approximately ____ voltage called ____ will be found across a parallel load

Answer 3

constant, Vz

Question 4

If the current through a Zener diode in breakdown is less than zero, then

Answer 4

the diode no longer controls the voltage across itself and therefore, any parallel loads

Question 5

True/False: The Zener diode has a non-zero Zener resistance, Rz

Answer 5

True

Question 6

In a pn junction diode, the point where the semiconductor material changes from p to n type is called the

Answer 6

metallurgical junction

Question 7

The pn junction diode is constructed using the impurity process called _____

Answer 7

doping

Question 8

The p-type region of a diode is also called the

Answer 8

anode (the arrow) +

Question 9

The n-type region of a diode is also called the

Answer 9

cathode (the line) -

Question 10

In a Conventional diode the + charge moves

Answer 10

the + charge moves in the direction opposite to current (electron flow)

Question 11

which is positive anode or cathode

Answer 11

the cathode attracts + charge. The anode attracts negative charge.

Question 12

Zener diodes are designed to operate in

Answer 12

reverse = Zener voltage otherwise in forward bias they drop only 0.7 volts

Question 13

Which transistor has the arrow of the emitter poiNting towards the base (PNP/NPN)

Answer 13

PNP

Question 14

How can one spot is the Bias is forward or reversed?

Answer 14

Negative to Positive is forwards
Positive to Positive is reversed
Compare to battery and resistors in circuit

Question 15

What makes silicon more desirable to use than germanium?

Answer 15

Silicon has more resistance to heat than germanium.

Question 16

What happens with a negative temperature coefficient?

Answer 16

Negative temperature coefficient means increase temperature=decrease in resistance.

Question 17

What are the two semiconductor elements suitable for electronic applications?

Answer 17

Silicon (Si) 0.7 VD
 and Germanium (Ge) 0.3 VD

Question 18

Crystal lattice structure is part of what?

Answer 18

Covalent bonding where 8 electrons are shared = a stable 8 electron arrangement

Question 19

Pentavalent is what type of impurity

Answer 19

N-type, pure semiconductor crystal with 5 electrons, CATHODE

Question 20

Trivalent is what type of impurity

Answer 20

P- type with 3 electrons and a semiconductor crystal, ANODE

Question 21

As temperature of a material increases it electrical resistance decreases

Answer 21

Negative Temperature Coefficient

Question 22

Silicon has__________resistance than germanium at room temperature

Answer 22

1000 times more

Question 23

Semiconductor materials .

Answer 23

Have characteristics that fall between insulators and conductors

Question 24

When using semiconductors, what is the major problem that must be controlled?

Answer 24

Heat and the changes caused by heat.

Question 25

Holes constantly drift towards

Answer 25

drift towards the NEGATIVE terminal of the voltage source.

Question 26

Electrons always flow

Answer 26

towards the POSITIVE terminal of the voltage source

Question 27

What are 2 pentavalent impurities?

Answer 27

Arsenic & Antimony

Question 28

What are 2 trivalent impurites?

Answer 28

Indium & Gallium

Question 29

Electrons in the outer band or shell of an element are characterized by their:

Answer 29

Energy

Question 30

The conductivity of P-type and N-type semiconductor materials depends on:

Answer 30

the doping level.

Question 31

A forward biased PN-junction conducts a current when:

Answer 31

a negative voltage source is connected to N-material.

Question 32

A forward biased PN-junction requires:

Answer 32

a negative voltage source connected to N-material.

Question 33

The reverse bias condition causes the barrier voltage to seemingly:

Answer 33

increase in level. unless it is a Zener diode

Question 34

A zener diode’s maximum current rating is determined principally by its:

Answer 34

maximum power dissipation.

Question 35

Zener diodes are used in two different ways to control voltage; these are called:

Answer 35

line or input and load regulation.

Question 36

In a zener diode, the cathode is:

Answer 36

a Z shaped bar.
indicated by a color band.
reverse biased.

Question 37

In testing a zener diode with a Digital Multimeter, what tests can be performed:

Answer 37

a continuity test.
reverse resistance test.
forward resistance test.

Question 38

In testing a diode with a Digital Multimeter, what tests can be performed:

Answer 38

continuity test.
reverse resistance test. (Infinity resistance)
forward resistance test. (low resistance)

Question 39

Dissipation of heat due to I^2R Loss with diodes and transistors are resolved by the use of

Answer 39

Heat sinks

Question 40

what acts as an acr suppressor, prevents insulation failure in windings and reduces heavy arcing

Answer 40

Freewheeling diodes

- Mathematically gives the load (parallel resistor) what it requires to remain balanced.

Question 41

What has a Reverse BIas

As brightness increases, current increases and is amplified by a transistor.

Answer 41

Photodiode image: arrow(s) pointing towards the anode/cathode >l

Question 42

What is Forward Bias

Voltage control during doping produces colour

Answer 42

LED image: arrow(s) pointing away l<
Red = less voltage
Amber = med voltage
Green = most voltage

Question 43

NPN and PNP are classed as what type of transistors

Answer 43

Bipolar- junction transistor

Question 44

The three parts or regions of a transistor are called:

Answer 44

emitter, base, collector.

Question 45

In order to perform voltage regulation using a zener diode, what other circuit component is required:

Answer 45

a series resistor