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neets 7 > CH 2 > Flashcards

CH 2 Flashcards

1
Q

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

A

Transistor

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2
Q

What electronic function made the transistor famous?

A

Amplification.

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3
Q

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

A

Outward.

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4
Q

What was the name of the very first transistor?

A

Point-contact.

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5
Q

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

A

Quality control.

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6
Q

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

A

Positive, more positive.

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7
Q

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

A

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

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8
Q

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

A

The P or base section.

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9
Q

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

A

98 percent.

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10
Q

What are the majority current carriers in a PNP transistor?

A

Holes.

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11
Q

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

A

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

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12
Q

What is the letter designation for base current?

A

I B.

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13
Q

Name the two current loops in a transistor.

A

The base current loop and the collector current loop.

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14
Q

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?

A

Amplifier.

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15
Q

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

A

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

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16
Q

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

A

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

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17
Q

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

A

The polarity of the source voltage.

18
Q

Which biasing method is the most unstable?

A

Base current bias or fixed bias.

19
Q

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

A

Self-bias.

20
Q

When is degeneration tolerable in an amplifier?

A

When it is necessary to prevent amplitude distortion.

21
Q

What is the most widely used combination-bias system?

A

The voltage-divider type.

22
Q 
What amplifier class of operation allows collector current to flow during the complete cycle of the
input?
A

Class A.

23
Q

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?

A

Cutoff.

24
Q

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

A

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

25
Q

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

A

Class A.

26
Q

What are the three transistor configurations?

A

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

27
Q

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

A

Common emitter.

28
Q

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

A

Base current (I B).

29
Q

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

A

Alpha ().

30
Q

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

A

Common base.

31
Q

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

A

I E.

32
Q

Which transistor configuration has the highest input resistance?

A

Common collector.

33
Q

What is the formula for GAMMA ()?

A

Y= I e/I b

34
Q

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

A

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

35
Q

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

A

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

36
Q

What is the greatest danger to a transistor?

A

Heat.

37
Q

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

A

The substitution method.

38
Q

What safety precaution must be taken before replacing a transistor?

A

The power must be removed from the circuit.

39
Q

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

A

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

40
Q

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

A

Gain and junction resistance.

41
Q

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

A

Normal gain.

42
Q

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

A

A leaking transistor

neets 7 (3 decks)

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