CH 2

Question 1

What is the name given to the semiconductor device that has three or more elements?

Answer 1

Transistor

Question 2

What electronic function made the transistor famous?

Answer 2

Amplification.

Question 3

In which direction does the arrow point on an NPN transistor?

Answer 3

Outward.

Question 4

What was the name of the very first transistor?

Answer 4

Point-contact.

Question 5

What is one of the most important parts of any transistor manufacturing process?

Answer 5

Quality control.

Question 6

To properly bias an NPN transistor, what polarity voltage is applied to the collector, and what is its relationship to the base voltage?

Answer 6

Positive, more positive.

Question 7

Why is conduction through the forward-biased junction of an NPN transistor primarily in one
direction, namely from the emitter to base?

Answer 7

Because the N material on one side of the forward-biased junction is more heavily doped than the P-material.

Question 8

In the NPN transistor, what section is made very thin compared with the other two sections?

Answer 8

The P or base section.

Question 9

What percentage of current in an NPN transistor reaches the collector?

Answer 9

98 percent.

Question 10

What are the majority current carriers in a PNP transistor?

Answer 10

Holes.

Question 11

What is the relationship between the polarity of the voltage applied to the PNP transistor and that applied to the NPN transistor?

Answer 11

The polarity of voltage applied to the PNP transistor is opposite of that applied to the NPN
transistor

Question 12

What is the letter designation for base current?

Answer 12

I B.

Question 13

Name the two current loops in a transistor.

Answer 13

The base current loop and the collector current loop.

Question 14

What is the name of the device that provides an increase in current, voltage, or power of a signal without appreciably altering the original signal?

Answer 14

Amplifier.

Question 15

Besides eliminating the emitter-base battery, what other advantages can different biasing methods offer?

Answer 15

Compensation for slight variations in transistor characteristics and changes in transistor
conduction because of temperature variations.

Question 16

In the basic transistor amplifier discussed earlier, what is the relationship between the polarity of the input and output signals?

Answer 16

The signals are opposite in polarity or 180 degrees out of phase with each other.

Question 17

What is the primary difference between the NPN and PNP amplifiers?

Answer 17

The polarity of the source voltage.

Question 18

Which biasing method is the most unstable?

Answer 18

Base current bias or fixed bias.

Question 19

What type of bias is used where only moderate changes in ambient temperature are expected?

Answer 19

Self-bias.

Question 20

When is degeneration tolerable in an amplifier?

Answer 20

When it is necessary to prevent amplitude distortion.

Question 21

What is the most widely used combination-bias system?

Answer 21

The voltage-divider type.

Question 22

What amplifier class of operation allows collector current to flow during the complete cycle of the
input?

Answer 22

Class A.

Question 23

What is the name of the term used to describe the condition in a transistor when the emitter-base junction has zero bias or is reverse biased and there is no collector current?

Answer 23

Cutoff.

Question 24

What two primary items determine the class of operation of an amplifier?

Answer 24

The amount of bias and the amplitude of the input signal.

Question 25

What amplifier class of operation is the most inefficient but has the least distortion?

Answer 25

Class A.

Question 26

What are the three transistor configurations?

Answer 26

Common emitter (CE), common base (CB), and common collector (CC).

Question 27

Which transistor configuration provides a phase reversal between the input and output signals?

Answer 27

Common emitter.

Question 28

What is the input current in the common-emitter circuit?

Answer 28

Base current (I B).

Question 29

What is the current gain in a common-base circuit called?

Answer 29

Alpha ().

Question 30

Which transistor configuration has a current gain of less than 1?

Answer 30

Common base.

Question 31

What is the output current in the common-collector circuit?

Answer 31

I E.

Question 32

Which transistor configuration has the highest input resistance?

Answer 32

Common collector.

Question 33

What is the formula for GAMMA ()?

Answer 33

Y= I e/I b

Question 34

List three items of information normally included in the general description section of a specification sheet for a transistor.

Answer 34

The kind of transistor, the transistor's common applications, and mechanical data.

Question 35

What does the number "2" (before the letter "N") indicate in the JAN marking scheme?

Answer 35

The number of junctions in the device, which in this case indicates a transistor.

Question 36

What is the greatest danger to a transistor?

Answer 36

Heat.

Question 37

What method for checking transistors is cumbersome when more than one transistor is bad in a circuit?

Answer 37

The substitution method.

Question 38

What safety precaution must be taken before replacing a transistor?

Answer 38

The power must be removed from the circuit.

Question 39

How is the collector lead identified on an oval-shaped transistor?

Answer 39

By the wide space between the collector lead and the other two leads (emitter and base).

Question 40

What are two transistor tests that can be done with an ohmmeter?

Answer 40

Gain and junction resistance.

Question 41

When you are testing the gain of an audio-frequency transistor with an ohmmeter, what is indicated by a 10-to-1 resistance ratio?

Answer 41

Normal gain.

Question 42

When you are using an ohmmeter to test a transistor for leakage, what is indicated by a low, but not shorted, reverse resistance reading?

Answer 42

A leaking transistor