Electronics

Question 1

A ________ is an electron that is in the outer shell of the atom and can be shared with other atoms to form covalent bonds

Answer 1

Valence electron

Question 2

A ________ is a chemical bond that involves the sharing of electron pairs between atoms

Answer 2

Covalent bond

Question 3

The best electrical conductors have ________ valence electrons

Answer 3

1-3

Question 4

The best insulators have ________ valence electrons

Answer 4

5-8

Question 5

________ have ________ valence electrons and are neither good
conductors, nor good insulators

Answer 5

Semiconductors, 4

Question 6

________ increases the conductivity of a semiconductor so that it is more comparable to a metal than an insulator

Answer 6

Doping

Question 7

Doping produces ________ and ________ semiconductors, depending on the material introduced to the pure silicon atoms

Answer 7

N-type, P-type

Question 8

How many valence electrons are there in a material used to create an N-type semiconductor?

Answer 8

Five. 4 of the 5 valence electrons in the pentavalent material form covalent bonds with the semiconductor, leaving one
electron free to move about. The excess electron makes the material more negative

Question 9

How many valence electrons are there in a material used to create a P-type semi conductor?

Answer 9

Three. The 3 valence electrons in the trivalent material form covalent bonds with the semiconductor, leaving one valence hole. This absence of electrons makes the material more positive

Question 10

Semiconductors have a negative temperature coefficient, meaning that as temperature ________, resistance ________

Answer 10

Increases, decreases

Question 11

Some semiconductor materials such as diodes and transistors will have ________ built into them to dissipate heat

Answer 11

Heat sink fins

Question 12

By connecting a P-type semiconductor with an N- type semiconductor we can create a diode. The P-type is referred to as the ________ of the diode and the N-type is the ________

Answer 12

Anode (+), Cathode (-)

Question 13

If a diode is specially constructed with materials such as gallium
arsenide, it will release energy in the form of visible light, making it a(n) ________

Answer 13

LED (Light emitting diode)

Question 14

Most common LED’s require a forward operating voltage of between approximately ________ volts with a forward current rating of about ________ milliamps

Answer 14

1.2-3.6, 10-50

Question 15

________ are similar to solar cells, in that they produce a small value of voltage when light strikes them

Answer 15

Photodiodes

Question 16

The ________ is made up of three layers of semiconductor material, and come in two types, ________ and ________

Answer 16

Bipolar-junction transistor, NPN, PNP

Question 17

A semiconductor atom, such as silicon, contains how many valence electrons?

Answer 17

4

Question 18

What is the name given to semiconductor materials that are doped with trivalent impurity atoms?

Answer 18

P-type

Question 19

What is the name given to semiconductor materials that are doped with pentavalent impurity atoms?

Answer 19

N-type

Question 20

Semiconductor materials exhibit a “negative temperature coefficient of resistance”. What does this mean?

Answer 20

When temperature increases, resistance decreases

Question 21

What is the typical voltage drop expected across a silicon diode that is conducting in forward bias?

Answer 21

0.7V

Question 22

What does the term ‘PIV’ mean?

Answer 22

Peak inverse voltage

Question 23

In order for a diode to conduct, the polarity of the cathode must be ________ with respect to the anode

Answer 23

Negative

Question 24

When using an ohmmeter for testing a diode, what indication would you expect (high or low) if the diode is shorted?

Answer 24

Low in both directions

Question 25

When using an ohmmeter for testing a diode, what indication would you expect (high or low) if the diode is open?

Answer 25

High in both directions

Question 26

When using an ohmmeter for testing a diode, what indication would you expect (high or low) if the diode is okay?

Answer 26

Low in one direction, high in the other

Question 27

What feature makes the Zener diode different from a conventional rectifier diode?

Answer 27

They conduct current without damaging themselves once their breakdown voltage is reached

Question 28

True or false: LEDs only emit light when forward biased

Answer 28

True

Question 29

How much is the forward bias barrier potential of a germanium diode?

Answer 29

0.3V

Question 30

Why is silicon more commonly used than germanium when constructing semiconductor devices?

Answer 30

Silicon can withstand higher temperatures

Question 31

True or false: the PIV of a rectifier diode gives its power rating, which is amps times volts

Answer 31

False

Question 32

True of false: the anode of a Zener diode must be connected to the positive terminal of a supply

Answer 32

False. This would mean the Zener diode is forward biased allowing current to flow through it with a typical 0.7V drop. Zener diodes must be placed in reverse bias in order for them to function properly and achieve their breakdown voltage

Question 33

True or false: when connecting a freewheeling diode, it must be connected in forward bias to the DC source

Answer 33

False. A freewheeling diode is an ordinary diode connected across an inductive load to protect the circuit from damage caused by sudden voltage spikes when the supply current is interrupted. Under normal conditions, it is connected in reverse bias and does not conduct current

Question 34

Bipolar Junction Transistors may be either ________ type or ________ type in their construction

Answer 34

PNP, NPN

Question 35

Two common types of semiconductors used in the construction of transistors are ________ and ________

Answer 35

P-type, N-type

Question 36

If an ohmmeter is used to test a good transistor, you should expect a ________ value of resistance when measuring across the base/emitter

Answer 36

Low

Question 37

If an ohmmeter is used to test a good transistor, you should expect a ________ value of resistance when measuring across the base/collector

Answer 37

High

Question 38

To identify voltage and current ratings for a given transistor, you should check the ________

Answer 38

Manufactures spec-sheet

Question 39

________ transistors are used for low power applications, and higher current rated transistors are called ________

Answer 39

Bi-polar junction, MOSFET transistors

Question 40

In a transistor amplifier circuit, increasing the ________ current should result in an increase in collector current

Answer 40

Base

Question 41

In an NPN transistor circuit, making the Base more positive will cause the collector current to ________ if the transistor is not saturated

Answer 41

Increase

Question 42

If Vce = Vcc, then the transistor is ________

Answer 42

Cut off

Question 43

The ratio of Ic to Ib is referred to as the ________ of a transistor

Answer 43

Beta, or amplification factor

Question 44

If Vbe for a silicon NPN transistor is 0.1V, then Ib is ________ and Ic is ________

Answer 44

Zero amps, zero amps

Question 45

Vbe for a conducting silicon transistor is approximately ________

Answer 45

0.7V