EDC 2

Question 1

The n-type regions in an npn bipolar
junction transistor are

A. collector, base, and emitter
B. base and emitter
C. collector and base
D. collector and emitter

Answer 1

D. collector and emitter

(look at the figure on your EDC 2 album baby)

Question 2

For normal operation of an npn
transistor, the base must be

A. positive with respect to the collector
B. negative with respect to the emitter
C. positive with respect to the emitter
D. disconnected

Answer 2

C. positive with respect to the emitter

For NORMAL operation of a transistor,
the B-E junction must be forward-biased. Therefore, for an NPN transistor,since the base is P type and the emitter is N type, for the B-E junction to beforward biased, the base must be more positive with respect to emitter.

Question 3

Beta (β) is the ratio of…

A. collector current to emitter current
B. collector current to base current
C. emitter current to base current
D. output voltage to input voltage

Answer 3

B. collector current to base current

Current gain for different BJT
configurations are as follows:
1. alpha = collector current/emitter current
2. beta = collector current/base current
3. gamma = emitter current/base current

Question 4

Where does the transistor act like an
open switch?

A. active region
B. inverted region
C. saturated region
D. cut off region

Answer 4

D. cut off region

In cut off region, both the junctions are
reverse biased. The transistor has
practically zero current because the
emitter does not emit charge carriers to the base. So, the transistor acts as open switch.

Question 5

Using the load line to answer, under
what condition will be Vce = Vcc?

A. Linear
B. Active
C. Cut-off
D. Saturation

Answer 5

C. Cut-off

At saturation : Vce = Vce(sat) ≈ 0 V
and lc = Ic(sat)
At the active or linear region:
VcE(sat) < Vce < Vcc and 0 < lc <
Ic(sat)
At cut-off: VcE ≈ Vcc and lc ≈0A

(see the fugure at EDC 2 album😚)

Question 6

If a certain transistor operates at the middle of the load line, an increase in the base resistance will move the Q point

A. Off the load line
B. Down
C. Nowhere
D. Up

Answer 6

B. Down

Increasing Rg → decreases lg→
decreases lc → Q point will be to a
lower position in the load line

(see the figure at EDC 2 album)

Question 7

An n-type semiconductor material

A. requires no doping
B. has trivalent impurity atoms added
C. is intrinsic
D. has pentavalent impurity atoms added

Answer 7

D. has pentavalent impurity atoms added

N-type semiconductor material, is an
extrinsic semiconductor material that is
the product of doping process that
involves adding donor impurities/
pentavalent atoms such as
Phosphorous, Antimony, Arsenic, or
Bismuth to an intrinsic Silicon or Germanium.

Question 8

The input impedance of a MOSFET is

A. higher than that of a JFET.
B. No different than that of a JFET
C. lower than that of a JFET.
D. approximately zero ohms.

Answer 8

A. higher than that of a JFET.

Zì(MOSFET) > Zì(JFET)&raquo_space; Zì(BJT)

Question 9

If a transistor operates at the middle of the load line, an increase in the current gain will move the Q point

A. Down
B. Up
C. Off the load line
D. Nowhere

Answer 9

B. Up

Increasing β → increases lc→Q point will move upward in the load line

(look at EDC 2 album)

Question 10

The point on the DC load line which is
represented by ‘Q’ is called_____

A. cut off point
B. breakdown point
C. operating point
D. cut in point

Answer 10

C. operating point

The point which represents the values of Ic and Vce that exist in a transistor circuit when no signal is applied is called as operating point. This is also called as working point or quiescent point.

Question 11

The input of a CB transistor is given
between_____

A. base and collector terminals
B. collector and emitter terminals
C. ground and emitter terminals
D. emitter and base terminals

Answer 11

D. emitter and base terminals

The name of the CB transistor says that
it’s a common based one. The input is
given between the emitter and base
terminals and the output is taken
between collector and base terminals.

Question 12

The primary difference between the construction of depletion-type and enhancement-type MOSFETs is

A. the size of the transistor
B. the reverse bias junction
C. All of these choices
D. the absence of the channel

Answer 12

D. the absence of the channel

EMOSFET is a like a normally-OFF
switch. A threshold voltage must be
exceeded by the gate to source voltage in order to create a conductive channel between the source and drain.
Therefore, at VGS still at O V there will be no conductive channel that will be created between the source and the drain.

Question 13

In the saturation region the collector-
base junction is _____ -biased and the base-emitter junction is _____ -biased for a transistor.

A. reverse, forward
B. forward, forward
C. reverse, reverse
D. forward, reverse

Answer 13

B. forward, forward

Question 14

Where should be the bias point set in order to make transistor work as an amplifier?

A. Cut off
B. Active
C. Saturation
D. Cut off and Saturation

Answer 14

B. Active

To operate transistor as an amplifier, it
requires more current amplification
factor and in cut off and saturation, the current amplification is less, therefore active region is better to fix the Q point.

Question 15

The base current is the _____ of the emitter and collector currents.

A. difference
B. sum
C. product
D. None of these choices

Answer 15

A. difference

Question 16

In BJT, the outer layers are the _____
sandwiched layer.

A. the same as
B. much smaller than
C. much larger than
D. None of these choices

Answer 16

C. much larger than

(go to your gallery for more EDC 2)

Question 17

When does the transistor act like an
open switch?

A. active region
B. saturated region
C. inverted region
D. cut off region

Answer 17

D. cut off region

In cut off region, both the junctions are
reverse biased. The transistor has
practically zero current because the
emitter does not emit charge carriers to the base. So, the transistor acts as open switch.

Question 18

If a splash of solder shorts the collector resistor of a CE NPN transistor amplifier configuration, the collector voltage will

A. Double
B. Stay the same
C. Drop to zero
D. Equal the collector supply voltage

Answer 18

D. Equal the collector supply voltage

From the output loop of a CE NPN
transistor: Vcc -IcRc - Vc = 0 If the
collector resistor will be shorted (Rc =0) the equation above can be simplified to: Vc= Vcc.

Question 19

For a transistor to function as an
amplifier,

A. Both the EB and CB junctions must be
forward-biased.
B. Both the EB and CB junctions must be
reverse-biased,
C. The CB junction must be forward-biased
and the EB junction must be reverse-
biased
D. The EB junction must be forward-
biased and the CB junction must be
reverse-biased.

Answer 19

D. The EB junction must be forward-
biased and the CB junction must be
reverse-biased.

Question 20

In a CE BJT NPN transistor amplifier, if the emitter resistance decreases, the collector voltage

A. Decreases
B. Increases
C. Breaks down the transistor
D. Stays the same

Answer 20

A. Decreases

In the output loop of a normal CE BJT NPN transistor amplifier: Vc =VcE +lgRE
Therefore if Re increases, Vc will
also increase.

Question 21

What should be the value of stability
factor to keep the operating point
stable?

A. zero
B. one
C. as high as possible
D. negative value

Answer 21

A. zero

Ideal value of stability factor = 0.

Question 22

Compared to NPN, the direction of
current is _____ and the polarity of the
voltage is _____ in a PNP transistor.

A. opposite; reverse
B. same; reverse
C. same; forward
D. opposite; forward

Answer 22

A. opposite; reverse

PNP and NPN transistors have different
construction therefore the flow of their
currents are opposite and the polarity of
the voltages required to bias them are
reverse of the other.

Question 23

An n-channel FETs are better as
compared to p-channel FET because

A. they are more efficient
B. mobility of electrons is more than that
of holes
C. they have high switching time
D. they have higher input impedance

Answer 23

B. mobility of electrons is more than that
of holes

Question 24

In a transistor, which is the largest of all
the doped regions?

A. The collector region
B. The emitter region
C. The base region
D. The anode region

Answer 24

A. The collector region

In BJTs, collector is the largest
region/layer while the smallest
layer/region is the sandwiched base
region/layer.

(see more at EDC 2 album)

Question 25

In an N-channel JFET, pinchoff occurs
when the gate bias is:

A. Zero
B. Very negative
C. Slightly positive
D. Slightly negative

Answer 25

B. Very negative

In an N-channel JFET, as the Gate
voltage is made more negative, the
width of the channel decreases until no
more current flows between the Drain
and the Source and the FET is said to be
“pinched-off” (similar to the cut-off
region for a BJT). The voltage at which the channel closes is called the “pinchoff voltage”,(VP).
For a P-channel JFET, same effect will happen but for an opposite polarity of gate voltage.

Question 26

In which JFET amplifier are the ac input
and output voltages 180° out of phase?

A. The common-source amplifier
B. The common-gate amplifier
C. The source-follower
D. The common-drain amplifier

Answer 26

A. The common-source amplifier

Input-output phase relationship for
different FET amplifier configurations:
Common-Gate : 0° or in-phase
Common-Drain or Source-Follower : 0°
or in-phase
Common-Source:180°

Question 27

In a transistor amplifier, when the Q
point moves along the load line, the
collector to emitter voltage increases
when the collector current_____

A. None of these choices
B. Increases
C. Stays the same
D. Decreases

Answer 27

D. Decreases

Moving upward or downward
along the load-line above, you will
notice that Ic and Vce will vary
inversely.

(see more at EDC 2 album)

Question 28

An enhancement-mode MOSFET can be
recognized in schematic diagrams by:

A. A broken vertical line inside the circle
B. An arrow pointing outward.
C. An arrow pointing inward
D. A solid vertical line inside the circle.

Answer 28

A. A broken vertical line inside the circle.

(see the figure in EDC 2 album)

Question 29

Which is not a MOSFET terminal?

A. Drain
B..Gate
C. Base
D. Source

Answer 29

C. Base

The three terminals of an FET (both
JFET and MOSFET) are GATE, DRAIN,and SOURCE. While for a BJT, the three terminals are BASE, COLLECTOR, and EMITTER.

Question 30

In an n channel JFET, the gate is

A. either n or p
B. p type
C. partially n & partially p
D. n type

Answer 30

B. p type

(see the N-Channel figure at EDC 2 album)

Question 31

an n-channel enhancement type
MOSFET, if the source is connected at a
higher potential than that of the bulk
(VSB > 0), the threshold voltage VT of
the MOSFET will

A. increase
B. decrease
C. change Polarity
D. remain unchanged

Answer 31

D. remain unchanged

V_T depends upon MOSFET
construction, hence it will Independent
from MOSFET parameters.

Question 32

The carriers of n channel JFET are

A. holes
B. free electrons or holes
C. free electrons and holes
D. free electrons

Answer 32

D. free electrons

In n type semiconductors carriers are
electrons. Since the JFET has an N-type material in the channel, current flowing from source to drain through channe
consists of free electrons only (since
FET is a unipolar device).

Question 33

Compared to bipolar junction transistor,
a JFET has

A. lower input impedance
B. high input impedance and high voltage gain
C. higher voltage gain
D. high input impedance and low voltage gain

Answer 33

D. high input impedance and low voltage gain

In a JFET input is reverse-biased while
in BJT the input is forward-biased.
Because of this, a JFET will have a higher input impedance but a lower voltage gain compared to a BJT.

Question 34

Which of the following devices has a
silicon dioxide layer?

A. JFET
B. NPN transistor
C. Tunnel diode
D. MOSFET

Answer 34

D. MOSFET

In MOSFETs (both depletion type and
enhancement type) the gate is insulated
from the channel by a layer of an
insulating material called Silicon Dioxide
or Si02.

Question 35

The primary advantage that MOSFET
transistors have over bipolar transistors
is_____.

A. higher switching speed
B. reduced propagation delay
C. high input impedance
D. low input impedance

Answer 35

C. high input impedance

A MOSFET has a higher input
impedance compared to a BJT since in MOSFET there is an insulating material between the gate and the channel.

Question 36

In a C-E configuration, an emitter
resistor is used for:

A. stabilization
B. higher gain
C. collector bias
D. ac signal bypass

Answer 36

A. stabilization

Adding an emitter resistor increases the stability but decreases the gain of a BJT CE amplifier.

Question 37

The symbol shown is for a…

(go to EDC 2 album)

A. N-channel DMOSFET
B. P-channel DMOSFET
C. N-channel JFET
D. P-channel JFET

Answer 37

A. N-channel DMOSFET

Question 38

Assertion (A): Two transistors one n-p-n
and the other p-n-p are identical in all
respects (doping, construction, shape,
size). The n-p-n transistor will have
better frequency response.

Reason (R): The electron mobility is
higher than hole mobility.

A. A is true but R is false
B. Both A and R are true and R is correct
explanation of A
C. Both A and R are true but R is not a correct
explanation of A
D. A is false but R is true

Answer 38

B. Both A and R are true and R is correct
explanation of A

NPN transistor will have a better
frequency response due to the fact that majority of the carriers in NPN are free electron and free electrons have higher mobility than holes making the NPN transistor more able to operate
satisfactorily at higher frequencies.

Question 39

As the temperature increases, β _____, VBE _____, and lco _____ in value for every 10°C.

A. decreases, increases, remains the same
B. increases, decreases, doubles
C. increases, increases, triples
D. decreases, increases, doubles

Answer 39

B. increases, decreases, doubles

As the temperature increases, β
increases, VBE decreases, and lco
doubles in value for every 10°C

Question 40

Which of the following applies to a safe
MOSFET handling?

A. Power should always be off when network
changes are made.
B. Always pick up the transistor by the casing.
C. All of these choices.
D. Always touch ground before handling the device.

Answer 40

C. All of these choices

MOSFETs are sensitive to electrostatic
discharge(ESD). Depending on the
energy of the pulse, electrostatic discharge (ESD) may cause either catastrophic failure (gate-oxide
breakdown) or non-catastrophic damage (degradation) to MOSFETs.

Question 41

Assertion (A): A JFET behaves as a
resistor when VGS < VP.
Reason (R): When VGS< VP, the drain
current in a JFET is almost constant.

A. Both A and R are true and R is correct
explanation of A
B. A is true but R is false
C. A is false but R is true
D. Both A and R are true but R is not a correct
explanation of A

Answer 41

B. A is true but R is false

Ohmic region: in this region FET is used
as a variable resistor.

Saturation or Active region: in this region
the FET is used for small signal amplification.

Breakdown region: operating in this
region may destroy the FET.

Question 42

The drain of FET is analogous to BJT

A. base
B collector
C. emitter
D. drain

Answer 42

B collector

Relation between BJT and FET
terminals:
Base →→ Gate
Collector → Drain
Emitter → Source

Question 43

Which of the following is the other name
for Common Drain Amplifier?

A. Current Booster
B. Voltage limiter
C. Voltage booster
D. Source Follower

Answer 43

D. Source Follower

Just like in BJT configurations,
Common Collector is also called Emitter
follower.

Question 44

The disadvantage of base bias is that

A. it is too beta dependent
B. it is very complex
C. it produces high leakage current
D. it produces low gain

Answer 44

A. it is too beta dependent

Base-bias or Fixed-bias in BJT
amplifiers provides the highest gain but is the most stable (parameter values are too beta dependent which can be easily affected by changes in temperature).