BIPOLAR JUNCTION TRANSISTORS

Question 1

A transistor amplifier has a voltage
gain of 100. If the input voltage is 75 mV,
the output voltage is:

Answer 1

7.5V

Question 2

What is the ratio of IC to IB?

Answer 2

either βDC or hFE, but not αDC

Question 3

For normal operation of a pnp BJT, the
base must be ________ with respect to
the emitter and ________ with respect
to the collector.

Answer 3

negative, positive

Question 4

When a transistor is used as a switch,
it is stable in which two distinct regions?

Answer 4

saturation and cut off

Question 5

The term BJT is short for

Answer 5

bipolar junction transistor

Question 6

For a silicon transistor, when a base-
emitter junction is forward-biased, it has
a nominal voltage drop of

Answer 6

0.7V

Question 7

A certain transistor has IC = 15 mA
and IB = 167µA; βDC is:

Answer 7

90

Question 8

What does βDC vary with?

Answer 8

both IC and ºC

Question 9

A BJT has an IB of 50µA and a βDC of
75; IC is:

Answer 9

3.75 mA

Question 10

What are the two types of bipolar
junction transistors?

Answer 10

npn and pnp

Question 11

The value of βDC

Answer 11

varies with temperature and
IC.

Question 12

A transistor data sheet usually
identifies βDC as

Answer 12

hFE.

Question 13

What is the ratio of IC to IE?

Answer 13

either βDC / (βDC + 1) or αDC, but
not βDC

Question 14

Which of the following is true
for an npn or pnp transistor?

Answer 14

IE = IB + IC

Question 15

What is the order of doping, from
heavily to lightly doped, for each region?

Answer 15

emitter, collector, base

Question 16

In what range of voltages is the
transistor in the linear region of its
operation?

Answer 16

0.7 < VCE < VCE(max)

Question 17

The magnitude of dark current in a
phototransistor usually falls in what
range?

Answer 17

nA

Question 18

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:

Answer 18

4.375 V

Question 19

What is (are) general-purpose/small-
signal transistors case type(s)?

Answer 19

TO-18
TO-92
TO-39
TO-52

Question 20

What is (are) common fault(s) in a
BJT-based circuit?

Answer 20

opens or shorts internal to the
transistor
open bias resistor(s)
external opens and shorts on
the circuit board

Question 21

The dc load line on a family of
collector characteristic curves of a
transistor shows the

Answer 21

saturation region.
cutoff region.
active region.