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AL-MC-Electronics / p.1
1.
(89-I-40)
3.
(91-I-43)
An n-p-n transistor is used in the above circuit as a
pulse shaper or a squarer. When a sinusoidal voltage
A CRO is used to display the current transfer
whose magnitude varies between +2 V and –2 V is
characteristic curve of a transistor. How should
applied to the input, what will be the output voltage?
points P, Q and R be connected to the X-input,
Y-input and the earth terminal of the CRO?
X-input
2.
Y-input
Earth
A.
P
Q
R
B.
P
R
Q
C.
Q
P
R
D.
Q
R
P
E.
R
P
Q
(90-I-39)
4.
(92-I-30)
The circuit above shows an NPN transistor and
two resistors 10 k  and 1 k  connected to a 5
V d.c. supply. The current gain of the transistor is
The graphs show the characteristics for a transistor
100. What is the value of the collector current?
operating in the common emitter mode. IC is the
collector current, IB is the base current and VCE is
B.
A
500 A
C.
5 mA
D.
50 mA
A.
20
E.
500 mA
B.
50
C.
80
D.
100
E.
150
A.
5
the potential difference between the collector and
emitter. The current gain for this transistor is
AL-MC-Electronics / p.2
5.
(92-I-31)
7.
(92-I-39)
The graph shows the transfer characteristic of an
electronic device.
In the circuit shown above,
D1 , D2 are two
diodes used to rectify a sinusoidal a.c. supply. Each
of the diodes has the I-V characteristic as shown.
For a current to flow through R, the minimum
The input is a sinusoidal voltage with a peak value
value of A is
of 1.5 V and a mean value of zero. Which one of
the following waveforms best represents the
A.
0.6 V
variation of the output voltage with time?
B.
1.2 V
C.
0.3
D.
(0.6)
2V
E.
(1.2)
2V
8.
2 V
(93-I-32)
Which of the following devices is/are used to store
energy?
6.
(92-I-32)
In the circuit above, what is the voltage
amplification?
A.
50000 with inversion
B.
1000 with inversion
C.
50 with inversion
D.
50 without inversion
E.
50000 without inversion
(1)
an inductor
(2)
a capacitor
(3)
a photocell
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Electronics / p.3
9.
(93-I-40)
Two electrical signals
V1 and V2 are fed into an
operational amplifier. The variations of
V1 and
V2 with time are shown above. Which of the
following graphs represents the variation of the
output
Vout with time?
The above diagrams show an NPN transistor
circuit and its input/output voltage characteristic.
What is the current amplification factor of the
transistor?
A.
10
11. (94-IIA-35)
B.
30
Which of the following statements about an
C.
60
operational amplifier is/are correct?
D.
75
E.
150
(1)
It amplifies the difference between the
voltage at its two inputs.
10.
(93-I-41)
(2)
For d.c., the open loop voltage gain is of the
(3)
order 10 .
For a.c., the open loop voltage gain decreases
5
with increasing frequency.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Electronics / p.4
12.
(94-IIA-36)
14.
(95-IIA-29)
A ‘black box’ containing two unknown
components is connected to a cell, a resistor and an
ammeter as shown
The above figure shows an operational amplifier
circuit which uses a
 15 V supply (not shown). If
the input potential is +0.5 V, what is the potential
at point X?
A current flows steadily no matter which way the
box’s terminals are connected to the cell and the
13.
A.
–5 V
same ammeter reading is obtained. The two
B.
–15 V
components in the ‘black box’ could be
C.
+0.5 V
D.
+5 V
A.
two diodes in series.
E.
+15 V
B.
two diodes in parallel.
C.
two capacitors in parallel.
D.
a diode and a resistor in parallel.
E.
a diode and a capacitor in parallel.
(94-IIA-39)
15.
(95-IIA-43)
An operational amplifier is connected as shown
below with input voltage
Vi   2 V
In the above circuit, the waveform across the diode
shown on the screen of the CRO should be
What is the output voltage
A.
-6 V
B.
–4 V
C.
+4 V
D.
+6 V
E.
+12 V
Vo ?
AL-MC-Electronics / p.5
16.
(96-IIA-30)
18.
(96-IIA-32)
Which of the following pairs of inputs would give a
HIGH output from the above combination of NAND
gates?
Input A
An input voltage ( Vin ) of 2.0 V is applied to an
Input B
ideal operational amplifier connected as shown. The
(1)
LOW
HIGH
(2)
LOW
LOW
(3)
HIGH
HIGH
current flowing through the 8 k  resistor is
A.
0.25 mA from X to Y.
B.
0.80 mA from X to Y.
A.
(1) only
C.
0.80 mA from Y to X.
B.
(3) only
D.
1.0 mA from X to Y.
C.
(1) and (2) only
E.
1.0 mA from Y to X.
D.
(2) and (3) only
E.
(1), (2) and (3)
19.
(97-IIA-32)
A circuit required for doubling the amplitude of a
17.
(96-IIA-31)
sinusoidal alternating voltage. Which of the
following circuits might be suitable?
In the above transistor circuit, the voltage across the
A.
(1) only
base and the emitter is 0.5 V when the transistor
B.
(3) only
works. The current amplification factor of the
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
transistor is 80. What input voltage ( Vin ) would
give an output voltage ( Vout ) of 4 V?
A.
0.25 V
B.
0.50 V
C.
0.75 V
D.
1.00 V
E.
1.25 V
AL-MC-Electronics / p.6
20.
(97-IIA-42)
22.
(00-IIA-29)
The figure shows a bridge rectifier circuit in which
all the diodes are assumed ideal. The source is a
In the above operational amplifier circuit, the output
voltage
21.
sinusoidal a.c. supply. Which of the following
traces (I, II or III) would be displayed on a CRO
Vout is
connected across the load resistor R if
A.
-5 V
B.
–2.5 V
(1)
the diode D were reversed in the circuit,
C.
0V
(2)
the diode D were removed leaving a break in
D.
+2.5 V
E.
+5 V
the circuit?
(98-IIA-40)
In the above circuit, the output voltage from the
operational amplifier is positive. Which of the
following changes could cause the output voltage to
change to negative?
R1
(1)
Increasing the value of
(2)
Decreasing the value of
(3)
Decreasing the light intensity on the LDR.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
R3
(1)
(2)
A.
I
II
B.
II
II
C.
II
III
D.
III
II
E.
III
III
AL-MC-Electronics / p.7
23.
(01-IIA-41)
25.
(02-IIA-34)
Which of the following is/are the advantage(s) of
using negative feedback in an operational amplifier
for voltage amplification?
i.
greater stability
ii.
larger voltage gain
iii.
no distortion of the output
A.
(1) only
In the above transistor circuit, the voltage across
B.
(3) only
the base and the emitter is 0.6 V when the
C.
(1) and (2) only
transistor conducts. The current amplification
D.
(2) and (3) only
factor of the transistor is 100. If the output voltage
is 2 V, what is the value of R?
26.
(02-IIA-43)
The figure shows a typical voltage-amplifier circuit
24.
A.
150 k 
built from a transistor with current gain 80. It
B.
270 k 
operates normally on a quiescent collector current
C.
300 k 
of 3 mA and with the base-emitter junction voltage
D.
540 k 
E.
600 k 
(02-IIA-33)
VBE  0.6 V . What should be the value of the
base bias resistor RB?
A.
B.
C.
D.
Which of the following combinations of a cell, an
ideal diode and a resistor will give the above I-V
relationship, where I and V are the applied current
and voltage respectively?
A.
B.
C.
D.
k
144 k
160 k
176 k
128
AL-MC-Electronics / p.8
27.
(02-IIA-44)
The figure shows an operational amplifier circuit.
When
V1  2.7 V and V0  0.9 V , what is
the potential at P?
A.
0V
B.
0.6 V
C.
2.1 V
D.
2.4 V