Deck 6: BJT Fumdamentals

Question 1

The dc beta is also known as the current gain because a small base current controls a much larger collector current.

Answer 1

True

Question 2

The middle region of a transistor is the ________.

A) collector
B) emitter
C) base
D) beta

Answer 2

C

Question 3

Which region of the transistor is physically the largest?

A) collector
B) emitter
C) base
D) beta

Answer 3

A

Question 4

The emitter current in a bipolar junction transistor is equal to the sum of the collector and base currents.

Question 5

The power rating of a transistor can be increased by using a heat sink.

Question 6

When the ground side of each voltage source is connected to the emitter of a bipolar junction transistor,it is called a common collector.

Question 7

The two junctions of a transistor are between the emitter and the base and between the

A) collector and emitter.
B) collector and base.
C) collector and beta.
D) base and committer.

Question 8

An unbiased transistor is like two back-to-back diodes.

Question 9

What is the semiconductor material generally used in the manufacturing process of transistors?

A) gallium
B) boron
C) copper
D) silicon

Question 10

In a system of analysis called h parameters,hFE is defined as the symbol for thermal resistance.

Question 11

A bipolar junction transistor has two doped regions.

Question 12

An unbiased transistor is like

A) a biased diode.
B) two diodes connected in parallel.
C) two back-to-back diodes.
D) two diodes connected in series with a capacitor.

Question 13

Transistor saturation and cutoff regions are useful in digital and computer circuits referred to as switching circuits.

Question 14

In an npn transistor,the emitter and collector are both n-type materials.

Question 15

When double-subscript notations are used and they are the same,the voltage represents a source.

Question 16

Small-signal transistors can dissipate less than 1 watt.

Question 17

A bipolar junction transistor should always operate in the breakdown region.

Question 18

The emitter of a bipolar junction transistor is lightly doped and the base is heavily doped.

Question 19

Surface-mount transistors are generally found in a simple three-terminal,gull-wing package.

Question 20

The dc beta is defined as the dc collector current divided by the dc emitter current.

Question 21

Transistors operate in the active,or linear region when they are used

A) as switching circuits.
B) to amplify weak signals.
C) as rectifiers.
D) in the breakdown region.

Question 22

On the set of collector curves,the horizontal part of the curve where the collector current is constant,is known as the

A) active region.
B) breakdown region.
C) saturation region.
D) cut-off region.

Question 23

The bulk resistance of the emitter diode becomes important

A) in low-power applications only.
B) in high-power applications only.
C) in low-frequency applications only.
D) in high-frequency applications only.

Question 24

When calculating base current for a germanium transistor circuit,the voltage base to emitter is approximated at ________.

A) 0.3 V
B) 0.7 V
C) 1.3 V
D) 1.7 V

Question 25

If the data sheet maximum rating,collector-emitter breakdown voltage is exceeded

A) current gain becomes maximum.
B) the emitter will become reverse biased.
C) the transistor will go into cut-off.
D) the transistor will breakdown and will probably be destroyed.

Question 26

Generally,power transistors can dissipate

A) less than 1 W.
B) more than 1 W.
C) more than 100 W.
D) less than 1 mW.

Question 27

Kirchoff's current law describes transistor currents as follows:

A) emitter current equals the sum of collector and base currents.
B) collector current equals the sum of base and emitter currents.
C) base current equals the sum of collector and emitter currents.
D) emitter current equals collector current minus the base current.

Question 28

In a common-emitter circuit,once the base current has been calculated,collector current can be determined by multiplying base current by ________.

A) alpha
B) the load resistor
C) maximum power rating
D) beta

Question 29

High-power transistors (over 1 W)typically have current gains of ________.

A) 1 to 10
B) 10 to 20
C) 20 to 100
D) 100 to 1000

Question 30

What type transistor connection is shown in Figure 6-7 (a)?

A) common emitter
B) common collector
C) common base
D) emitter follower

Question 31

The base region of a transistor is

A) lightly doped and very thick.
B) lightly doped and very thin.
C) heavily doped and very thick.
D) heavily doped and very thin.

Question 32

An instrument that graphically displays collector current versus the collector to emitter voltage is

A) a voltmeter.
B) a logic probe.
C) an oscilloscope.
D) a curve tracer.

Question 33

A transistor's current gain is equal to

A) collector current divided by emitter current.
B) emitter current divided by base current.
C) collector current divided by base current.
D) base current divided by collector current.

Question 34

The type of biasing that produces the most useful results is

A) forward-biasing the emitter diode and reverse-biasing the collector diode.
B) reverse-biasing the emitter diode and forward-biasing the collector diode.
C) forward-biasing the collector diode and reverse-biasing the base diode.
D) reverse-biasing the collector diode and forward-biasing the base diode.

Question 35

When working with transistor circuits,single subscripts are used to denote

A) voltage sources.
B) current sources.
C) node voltages.
D) Thevenin's voltages.

Question 36

When using double-subscript notation with transistor circuits and the subscripts are the same,the voltage represents

A) the voltage between two points.
B) a voltage source.
C) an ac source.
D) the Thevenin's voltage.

Question 37

A transistor has a power dissipation that equals ________.

A) VCE x RC
B) V_CE x P_D
C) V_CE x I_C
D) V_CE x I_B

Question 38

What is the purpose of R_B in the circuit shown in Figure 6-7 (a)?

A) load resistor
B) filtering
C) limit current
D) amplify VBB

Question 39

Transistor saturation and cutoff regions are used in circuits referred to as ________.

A) rectifiers
B) filters
C) switching circuits
D) amplifiers

Question 40

What is the source of bias for the transistor's emitter diode shown in Figure 6-7 (a)?

A) ^VCC
B) VBB
C) VCE
D) RC

Question 41

What is the device that increases a transistor's power rating by reducing the internal heat faster?

A) heater wire
B) chassis
C) grommet
D) heat sink

Question 42

The only way to keep a transistor case temperature at 25°C when the ambient temperature is 25°C is

A) to keep refrigerated.
B) by keeping equipment chassis open.
C) by bringing room temperature below 21°C.
D) by fan-cooling or by using a heat sink.

Question 43

What is the surface-mount package called that resembles the dual-inline package and houses multiple transistors?

A) SOT
B) FET
C) BJT
D) SOIC

Question 44

What type of transistor is usually found in a simple three-terminal,gull-wing package?

A) chassis mount
B) printed-circuit
C) surface-mount
D) power

Question 45

In most applications,a small-signal transistor is not fan-cooled

A) but it does have a heat sink.
B) and it does not have a heat sink.
C) but it can be used as a power transistor.
D) and case temperatures are usually above 30°C.

Question 46

When working with h parameter analysis,the symbol for current gain is ________.

A) bDC
B) hFE
C) ^aFED.
D) D

Question 47

What is the possible problem if B is equal to 15 V and C is equal to 15 V?

A) transistor is blown open
B) V_BB is 0 V
C) transistor is shorted
D) V_CC is 0 V

Question 48

What is the possible problem if B is equal to 0 V and C is equal to 15 V?

A) transistor is shorted
B) R_B is open
C) V_CC is 0 V
D) transistor is blown open

Question 49

The data sheet entry that lists how much the power rating of a device has to be reduced is the

A) maximum power factor.
B) maximum power dissipation.
C) derating factor.
D) breakdown factor.

Question 50

Data sheet entries that allow a designer to work out the case temperature for different heat sinks are called ________.

A) thermal resistances
B) thermal shocks
C) reverse breakdown resistances
D) negative resistances