Deck 4: Bipolar Junction Transistors

Question 1

Refer to the figure above. If the value of VBB were increased to 10 V, the transistor would be operating in

A)the active region.
B)cutoff.
C)saturation.
D)Cannot be determined.

Answer 1

C

Question 2

The base- to- emitter junction of a certain transistor is checked with a DMM on diode check in the forward bias direction. If the DMM indicates 0.700, the transistor is

A)germanium and measuring normal.
B)open between the base and emitter.
C)silicon and measuring normal.
D)definitely defective.

Answer 2

C

Question 3

A BJT has an IB of 75 µA and a fidc of 100. The value of IC is

A)7.5 mA.
B)10 mA.
C)75 mA.
D)175 µA.

Answer 3

A

Question 4

An open base resistor RB)in a transistor switch will result in the

A)transistor being instantly destroyed.
B)transistor always being ON.
C)transistor always being OFF.
D)transistor operating in the active region.

Question 5

Refer to the figure above. This circuit is operating

A)in saturation.
B)in the active region.
C)incorrectly because the bias voltages are wrong.
D)in cutoff.

Question 6

Refer to the figure above. The value of IB is

A)8.6 mA.
B)860 µA.
C)0.7 µA.
D)1 mA.

Question 7

Refer to the figure above. If this transistor is operating in saturation, the value of ICsat)is

A)42.6 mA.
B)4.26 mA.
C)9.4 mA.
D)28.6 mA.

Question 8

The signal voltage gain of an amplifier, AV, is defined as

A)AV = IB x RB.
B)AV = Rc .
C)AV = Vout .
D)AV = r'e .
Vin RC

Question 9

When a transistor switch is on, the collector current is limited by

A)the base voltage.
B)the collector resistance.
C)the base current.
D)the base resistance.

Question 10

Besides operating as an amplifier, the BJT is often applied as a

A)varactor.
B)voltage controlled capacitance.
C)variable inductor.
D)switch.

Question 11

Normal operation of an NPN BJT requires the base to be _ with respect to the emitter, and with respect to the collector.

A)negative, negative
B)positive, negative
C)positive, positive
D)negative, positive

Question 12

The symbol hFE is the same as

A)fiDC.
B)aDC.
C)fiac.
D)hj- fj.

Question 13

VCE approximately equals when a transistor switch is in saturation.

A)0.7 V
B)VB
C)VC
D)0.2 V

Question 14

Most of the electrons in the base of an NPN transistor flow

A)into the collector.
B)out of the base lead.
C)into the base supply.
D)into the emitter.

Question 15

Refer to the figure above. If the value of the collector resistor is increased to 6.8 k▲, the new value of ICsat)is

A)2.13 mA.
B)1.47 mA.
C)0.68 mA.
D)0 mA.

Question 16

The signal output voltage Vout)is a function of the

A)changing collector current IC)through the collector resistor RC.
B)current from base to collector.
C)voltage drop from base to collector.
D)power being dissipated by the base supply voltage.

Question 17

If the collector resistance in a transistor amplifier is open, the dc voltage at the collector will be closest to

A)VCC.
B)VCC/2.
C)VBB.
D)0 V.

Question 18

A transistor collector characteristic curve is a graph showing

A)emitter current IE)versus collector- emitter voltage VCE)for specified values of base current IB).
B)collector current IC)versus collector- emitter voltage VC)for specified values of base current IB).
C)collector current IC)versus collector- emitter voltage VCC)for specified values of base current IB).
D)collector current IC)versus collector- emitter voltage VCE)for specified values of base current IB).

Question 19

The base of an NPN transistor is thin and

A)lightly doped.
B)doped by a pentavalent material.
C)metallic.
D)heavily doped.

Question 20

A transistor amplifier has an input voltage of 67 mV and an output voltage of 2..48 V. The voltage gain is

A)27.
B)67.
C)17.
D)37.

Question 21

A 22 mV signal is applied to the base of a properly biased transistor that has an r'e = 7 ▲ and an RC = 1.2 k▲. The output voltage at the collector is

A)17.1 V.
B)3.77 V.
C)22 mV.
D)7 V.

Question 22

In a bipolar junction transistor, collector current is controlled by

A)base current.
B)collector voltage.
C)collector resistance.
D)All of the above.

Question 23

In an NPN transistor, the majority carriers in the base are

A)free electrons.
B)holes.
C)Neither A nor B.
D)Both A and B.

Question 24

A transistor has a fiDC of 250 and a base current, IB, of 20 µA. The collector current, IC, equals

A)5 mA.
B)50 mA.
C)5 A.
D)500 µA.

Question 25

When a transistor is operated in the active region, changes in the collector supply voltage VCC

A)produce changes in collector current.
B)have little or no effect on collector current.
C)produce changes in base voltage.
D)produce changes in emitter voltage.

Question 26

A bipolar junction transistor has regions of operation.

A)1
B)2
C)3
D)4

Question 27

A certain transistor has an IC = 12 mA and an IB = 125 µA. fidc is

A)15.
B)96.
C)12.
D)150.

Question 28

When transistors are used in digital circuits they usually operate in the

A)active region.
B)saturation and cutoff regions.
C)linear region.
D)breakdown region.

Question 29

The region in a transistor that has to dissipate the most heat is the

A)anode.
B)emitter.
C)base.
D)collector.

Question 30

A 35 mV signal is applied to the base of a properly biased transistor with an r'e = 8 ▲ and RC = 1 k ▲. The output signal voltage at the collector is

A)4.375 mV.
B)28.57 V.
C)4.375 V.
D)3.5 V.

Question 31

Refer to the figure above. This circuit is saturated. To get the circuit to operate close to its linear range

A)RB should be decreased.
B)RB should be increased.
C)RC should be decreased.
D)Vin should be increased.

Question 32

In a transistor, the relation of the three transistor currents is

A)IC = IB - 2IE.
B)IE = IC + IB.
C)IC = IE + VC/RC.
D)IC = IE + IB.

Question 33

Refer to the figure above. The voltage VCE was measured and found to be 20 V. The transistor is operating in

A)saturation.
B)the active region.
C)cutoff.
D)Not enough data to determine.