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WorksheetsBipolar Junction Transistor
Total questions: 75
Worksheet time: 38mins
A transistor has …………………
one pn junction
two pn junctions
three pn junctions
four pn junctions
The number of depletion layers in a transistor is …………
four
three
one
two
The base of a transistor is ………….. doped
heavily
moderately
lightly
none of the above
The element that has the biggest size in a transistor is ………………..
collector
base
emitter
collector-base-junction
In a pnp transistor, the current carriers are ………….
acceptor ions
donor ions
free electrons
holes
The collector of a transistor is …………. doped
heavily
moderately
lightly
none of the above
A transistor is a …………… operated device
current
voltage
both voltage and current
none of the above
In a npn transistor, ……………. are the minority carriers
free electrons
holes
donor ions
acceptor ions
The emitter of a transistor is ………………… doped
lightly
heavily
moderately
none of the above
In a transistor, the base current is about ………….. of emitter current
25%
20%
35 %
5%
At the base-emitter junctions of a transistor, one finds ……………
reverse bias
a wide depletion layer
low resistance
none of the above
The input impedance of a transistor is ………….
high
low
very high
almost zero
Most of the majority carriers from the emitter ………………..
recombine in the base
recombine in the emitter
pass through the base region to the collector
none of the above
The current IB is …………
electron current
hole current
donor ion current
acceptor ion current
In a transistor ………………..
IC = IE + IB
IB = IC + IE
IE = IC – IB
IE = IC + IB
The value of α of a transistor is ……….
more than 1
less than 1
1
none of the above
IC = αIE + ………….
IB
ICEO
ICBO
βIB
The output impedance of a transistor is ……………..
high
zero
low
very low
In a tansistor, IC = 100 mA and IE = 100.2 mA. The value of β is …………
100
50
about 1
200
In a transistor if β = 100 and collector current is 10 mA, then IE is …………
100 mA
100.1 mA
110 mA
none of the above
The relation between β and α is …………..
β = 1 / (1 – α )
β = (1 – α ) / α
β = α / (1 – α )
β = α / (1 + α )
The value of β for a transistor is generally ………………..
1
less than 1
between 20 and 500
above 500
The most commonly used transistor arrangement is …………… arrangement
common emitter
common base
common collector
none of the above
The input impedance of a transistor connected in …………….. arrangement is the highest
common emitter
common collector
common base
none of the above
The output impedance of a transistor connected in ……………. arrangement is the highest
common emitter
common collector
common base
none of the above
The phase difference between the input and output voltages in a common base arrangement is …………….
180o
90o
270o
0o
The power gain in a transistor connected in ……………. arrangement is the highest
common emitter
common base
common collector
none of the above
The phase difference between the input and output voltages of a transistor connected in common emitter arrangement is ………………
0o
180o
90o
270o
The voltage gain in a transistor connected in ………………. arrangement is the highest
common base
common collector
common emitter
none of the above
As the temperature of a transistor goes up, the base-emitter resistance ……………
decreases
increases
remains the same
none of the above
The voltage gain of a transistor connected in common collector arrangement is ………..
equal to 1
more than 10
more than 100
less than 1
The phase difference between the input and output voltages of a transistor connected in common collector arrangement is ………………
180o
0o
90o
270o
IC = β IB + ………..
ICBO
IC
ICEO
αIE
IC = [α / (1 – α )] IB + ………….
ICEO
ICBO
IC
(1 – α ) IB
IC = [α / (1 – α )] IB + […….. / (1 – α )]
ICBO
ICEO
IC
IE
BC 147 transistor indicates that it is made of …………..
germanium
silicon
carbon
none of the above
ICEO = (………) ICBO
β
1 + α
1 + β
none of the above
A transistor is connected in CB mode. If it is not connected in CE mode with same bias voltages, the values of IE, IB and IC will …………..
remain the same
increase
decrease
none of the above
If the value of α is 0.9, then value of β is ………..
9
0.9
900
90
In a transistor, signal is transferred from a …………… circuit
high resistance to low resistance
low resistance to high resistance
high resistance to high resistance
low resistance to low resistance
The arrow in the symbol of a transistor indicates the direction of ………….
electron current in the emitter
electron current in the collector
hole current in the emitter
donor ion current
The leakage current in CE arrangement is ……………. that in CB arrangement
more than
less than
the same as
none of the above
A heat sink is generally used with a transistor to …………
increase the forward current
decrease the forward current
compensate for excessive doping
prevent excessive temperature rise
The most commonly used semiconductor in the manufacture of a transistor is ………….
germanium
silicon
carbon
none of the above
The collector-base junction in a transistor has ……………..
forward bias at all times
reverse bias at all times
low resistance
none of the above
When transistors are used in digital circuits they usually operate in the ………….
active region
breakdown region
saturation and cutoff regions
linear region
Three different Q points are shown on a dc load line. The upper Q point represents the ………….
minimum current gain
intermediate current gain
maximum current gain
cutoff point
A transistor has a β DC of 250 and a base current, IB, of 20 μA. The collector current, IC, equals to …………….
500 μA
5 mA
50 mA
5 A
A current ratio of IC/IE is usually less than one and is called …………
beta
theta
alpha
omega
With the positive probe on an NPN base, an ohmmeter reading between the other transistor terminals should be ……
open
infinite
low resistance
high resistance
In a CE configuration, an emitter resistor is used for ……
stabilization
ac signal bypass
collector bias higher gain
higher gain
Voltage-divider bias provides ……….
an unstable Q point
a stable Q point
a Q point that easily varies with changes in the transistor’s current gain
a Q point that is stable and easily varies with changes in the transistor’s current gain
To operate properly, a transistor’s base-emitter junction must be forward biased with reverse bias applied to which junction?
collector-emitter
base-collector
base-emitter
collector-base
The ends of a load line drawn on a family of curves determine ……
saturation and cutoff
the operating point
the power curve
the amplification factor
If VCC = +18 V, voltage-divider resistor R1 is 4.7 kilo ohm , and R2 is 1500 ohm , then the base bias voltage is ……….
8.7 V
4.35 V
2.9 V
0.7 V
The C-B configuration is used to provide which type of gain?
voltage
current
resistance
power
The Q point on a load line may be used to determine …………
VC
VCC
VB
IC
A transistor may be used as a switching device or as a ………….
fixed resistor
tuning device
rectifier
variable resistor
If an input signal ranges from 20–40 A (microamps), with an output signal ranging from .5–1.5 mA (milliamps), what is the ac beta?
0.05
20
50
500
Beta’s current ratio is ……..
IC/IB
IC/IE
IB/IE
IE/IB
A collector characteristic curve is a graph showing ………..
emitter current (IE) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant
collector current (IC) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant
collector current (IC) versus collector-emitter voltage (VC) with (VBB) base bias voltage held constant
collector current (IC) versus collector-emitter voltage (VCC) with (VBB) base bias voltage held constant
With low-power transistor packages, the base terminal is usually the ……….
tab end
middle
right end
stud mount
When a silicon diode is forward biased, VBE for a CE configuration is ……..
voltage-divider bias
0.4 V
0.7 V
emitter voltage
What is the current gain for a common-base configuration where IE = 4.2 mA and IC = 4.0 mA?
16.8
1.05
0.2
0.95
With a PNP circuit, the most positive voltage is probably …………
ground
VC
VBE
VCC
If a 2 mV signal produces a 2 V output, what is the voltage gain?
0.001
0.004
100
1000
Most of the electrons in the base of an NPN transistor flow …………
out of the base lead
into the collector
into the emitter
into the base supply
In a transistor, collector current is controlled by ………..
collector voltage
base current
collector resistance
all of the above
Total emitter current is …………
IE – IC
IC + IE
IB + IC
IB – IC
Often a common-collector will be the last stage before the load; the main function(s) of this stage is to ………….
provide voltage gain
provide phase inversion
provide a high-frequency path to improve the frequency response
buffer the voltage amplifiers from the low-resistance load and provide impedance matching for maximum power transfer
For a CC configuration to operate properly, the collector-base junction should be reverse biased, while forward bias should be applied to …………… junction.
collector-emitter
base-emitter
collector-base
cathode-anode
The input/output relationship of the common-collector and common-base amplifiers is ………..
270 degrees
180 degrees
90 degrees
0 degrees
If a transistor operates at the middle of the dc load line, a decrease in the current gain will move the Q point ………….
off the load line
nowhere
up
down
Which is the higher gain provided by a CE configuration?
voltage
current
resistance
power
What is the collector current for a CE configuration with a beta of 100 and a base current of 30 μA?
30 μA
0.3μA
3 mA
3 MA
