TYPICAL QUESTIONS &
ANSWERS
PART
- I
OBJECTIVE TYPE QUESTIONS
Each
Question carries 2 marks.
Choose
correct or the best alternative in the following:
Q.1 The “Superposition
theorem” is essentially based on the concept of
(A) duality. (B)
linearity.
(C) reciprocity. (D) non-linearity.
Ans: B
Q.2 Cells are connected
in parallel in order to
(A)
increase the voltage available. (B) reduce cost
of wiring.
(C) increase the current available. (D) reduce the
time required to fully
charge them after use.
Ans: C
Q.3 The power factor of a purely resistive
circuit is
(A) zero. (B) unity.
(C)
lagging. (D) leading.
Ans: B
Q.4 The power taken by a 3-phase load is
given by the expression
(A) 
. (B) 
.
(C) 
. (D) 
.
Ans: B
Q.5 Which of the following generating
stations has the minimum running cost?
(A) hydro-electric station. (B) nuclear power station.
(C) thermal power station. (D)
diesel power plant.
Ans: A
Q.6 Which of the following motors has a high
starting torque?
(A)
ac series motor. (B) dc series motor.
(C) induction motor. (D) synchronous motor.
Ans: B
Q.7 A step-up transformer increases
(A) voltage. (B) current.
(C) power. (D) frequency.
Ans: A
Q.8 The effect of increasing the length of
the air gap in an induction motor will be to increase
(A) power factor. (B)
speed.
(C) magnetising current. (D) air-gap flux.
Ans: C
Q.9 The combined
resistance of two equal resistors connected in parallel is equal to
(A) One half the resistance of one resistor.
(B)
Twice the resistance of one
resistor.
(C)
Four times the
resistance of one resistor.
(D)
One fourth the
resistance of one resistor.
Ans: A
Q.10 Superposition theorem can be applicable only to circuits having _________ elements.
(A)
Non- linear (B) Passive
(C) Resistive (D) Linear bilateral
Ans: D
Q.11 The Q- factor of a coil is given by
(A) Its power factor cos j.
(B)
Ratio of max. energy stored & energy dissipated per
cycle..
(C)
Reciprocal of its power factor.
(D)
Ratio R/Z.
Ans: C
Q.12 Voltage equation of a dc motor is
(A) V = Eb + Ia
Ra. (B)
Eb = V + Ia Ra.
(C) V = Eb / Ia Ra. (D) V = Eb
+ Ia 2Ra.
Ans: A
Q.13 The efficiency of a transformer is maximum when
(A) It runs at half full load. (B) It runs at full load.
(C) Its Cu loss equals iron loss. (D) It runs overload.
Ans: C
Q.14 The crawling in an induction motor is caused by
(A) Improper design of
the machine (B) Low voltage supply.
(C) High loads. (D) Harmonics developed in the motor.
Ans: D
Q.15 The starting winding of a single-phase motor is placed in
(A)
Rotor. (B) Stator.
(C) Armature. (D) Field.
Ans: B
Q.16 Reduction in the capacitance of a capacitor- start motor results in reduced
(A)
Noise. (B)
Speed.
(C) Starting torque. (D) Armature
reaction.
Ans: C
Q.17 In an ac circuit, the ratio of kW / kVA represents
(A) Power factor. (B) Load
factor.
(C) Form factor. (D) Diversity
factor.
Ans: A
Q.18 The unit of inductance is
(A) Ohm. (B)
Mho.
(C) Farad. (D)
Henry.
Ans: D
Q.19 Thevenin’s equivalent
circuit consists of _________.
(A) Series combination of RTh, ETh
and RL.
(B)
Series combination of RTh,
ETh.
(C) Parallel combination
of RTh, ETh.
(D) Parallel combination
of RTh, ETh and RL.
Ans:
B
Q.20 In an R – L –C circuit, the phase of the current with respect to the circuit voltage will be_________.
(A)
Leading. (B) Same.
(C) Lagging. (D) Depends upon the value of Land C.
Ans: D
Q.21 The frequency of DC supply is__________.
(A) Zero. (B) 16 ⅔ Hz.
(C) 50 Hz. (D) 100 Hz.
Ans: A
Q.22 Load factor is defined as the ratio of _________.
(A)
Average
Demand / Max. Demand.
(B)
Max. Demand / Average Demand.
(C)
Average Demand / Connected load.
(D) Connected load / Max. Demand.
Ans: A
Q.23 Static Capacitors are used for__________.
(A) Power improvement. (B) Current improvement.
(C) Voltage improvement. (D) Power factor improvement.
Ans: D
Q.24 The speed of an induction motor__________.
(A) Decreases too much
with the increase of load.
(B)
Increases with the increase of load.
(C)
Decreases slightly with the increase of load.
(D)
Remains constant with the increase of load.
Ans: C
Q.25 Centrifugal switch is provided for disconnecting the auxiliary winding in a_______.
(A) Capacitor- start
motor. (B) Capacitor run motor.
(C) Reluctance motor. (D)
Hysteresis motor.
Ans: A
Q.26 Rotating magnetic field is produced in a ________.
(A) Single- phase induction motor. (B) Three- phase induction motor.
Ans: B
Q.27 The frequency of the secondary voltage of a transformer will be_________.
(A) Less than the frequency of the primary voltage.
(B) Equal to the primary voltage.
(C) Greater than the
frequency of the primary voltage.
(D) Very much greater
than the frequency of the primary voltage.
Ans: B
Q.28 The demand factor for the electrical system is the ratio of
(A) Maximum demand to connected load
(B) Maximum demand to average load
(C) Average power to maximum power
(D) Relative power to total power
Ans:
A
Q.29 When a low resistance is
connected in parallel with a high resistance, the combined resistance is
(A) Always more than the high resistance.
(B)
Always less than the low resistance.
(C)
Always between the high resistance & low resistance.
(D)
Either lower or higher than low resistance depending on the
value of high resistance.
Ans: B
Q.30 Q factor of an
inductive coil is given by
(A) R/Z (B)
(C) 
(D)
l
r/l
Ans: B
Q.31 The r.m.s. value of sinusoidal 100 V peak to peak is _________ volt.
(A)
(B) 
(C) 50 (D) 100
Ans:
B
Q.32 If the readings of the two wattmeters in the 2-wattmeter method of power measurement are 4.5 kW and 3.5 kW respectively and the latter reading has been obtained after reversing the current coil of the wattmeter. What will be the total power in kW?
(A) 1 (B) 3.5
(C) 4.5 (D)
8
Ans: A
Q.33 A DC series motor is best suited for driving
(A) Lathes. (B) Cranes and hoists.
(C) Shears and punches. (D) Machine tools.
Ans: B
Q.34 Transformer cores are built up from laminations rather than from solid metal so that
(A) Oil penetrates the
core more easily.
(B) Eddy current loss is
reduced.
(C)
Less lamination is required for the windings.
(D)
Turn ratio is higher
than voltage ratio.
Ans: B
Q.35 In a DC series motor increase in load current results in
(A) Decrease in speed (B) Increase in speed
(C) Better commutation (D) Increase in the
back emf.
Ans: A
Q.36 The starting torque of a 1-phase induction motor is
(A) High. (B) Moderate.
(C) Low. (D)
Zero.
Ans: D
Q.37 An electric motor in which rotor and stator fields rotate simultaneously is called a __________ motor.
(A) DC (B) Induction
(C) Synchronous (D) Universal
Ans: C
Q.38 In
(A) 1 – phase a.c. system. (B)
3-wire
(C) 3-phase 3-wire a.c. system. (D) 2-wire
Ans:
C
Q.39 In ac circuit the product of voltage and current is known as
(A) Power. (B) Real power.
(C) Resistive power. (D) Apparent power.
Ans:
D
Q.40 A network that does not have either voltage or current sources is called
(A) Active network. (B) Passive network.
(C) Resistive network. (D) Dummy network.
Ans:
B
Q.41 The Power- factor at resonance in R-L-C circuit is
(A) Zero. (B) Unity.
(C) 0.5 lagging. (D) 0.5 leading.
Ans: B
Q.42 In an 8 – pole wave connected motor armature, the number of parallel paths are
(A) 8 (B) 4
(C) 2 (D) 1
Ans:
C
Q.43 Transformer core is laminated to
(A) Reduce the copper losses. (B) Reduce the core losses.
(C) Reduce the eddy current losses. (D) None of these.
Ans:
C
Q.44 The relation between frequency, speed and number of poles is given by
(A) 
(B) 
(C) 
(D) 
Ans: A
Q.45 Star – delta starter of an induction motor
(A) Inserts resistance in rotor circuit.
(B) Inserts resistance in stator circuit.
(C) Applies reduced voltage to rotor.
(D) Applies reduced voltage to stator.
Ans: D
Q.46 Stator core of an induction motor is made of
(A) Laminated cast iron. (B) Mild steel.
(C) Silicon steel stampings. (D) Soft wood.
Ans:
C
Q.47 Watt hour is the unit of
(A) Electric power. (B) Electric capacity.
(C) Electric energy. (D) Electric charge.
Ans:
C
Q.48 A battery is a source of
(A) DC voltage. (B) 1 f AC voltage.
(C) 3 f AC voltage. (D) AC or DC voltage.
Ans: A
Q.49 Which DC motors has approximately constant speed?
(A) Series motor. (B) Shunt motor
(C) Cumulatively compound motor (D) All of the above.
Ans:
B
Q.50 Which of the following bulbs will have the least resistance?
(A) 220V, 60W (B) 220 V, 100 W
(C) 115 V, 60 W (D) 115V, 100 W
Ans:
D
Q.51 Resistance of a wire is r ohms. The wire is stretched to double its length, then its resistance in ohms is
(A) r/2 (B) 4r
(C) 2r (D) r/4
Ans:
B
Q.52 An electric machine will have high efficiency when
(A) input/output ratio is low (B) reactive power is more
(C) kWh consumption is low (D) losses are low
Ans:
D
Q.53 Which type of loss is not common to transformers and rotating machines?
(A) Eddy current loss (B) Copper loss
(C) Hysteresis loss (D) Windage loss
Ans:
D
Q.54 The difference between the synchronous speed and the actual speed of an induction motor is known as
(A) Regulation (B) back lash
(C) slip (D) lag
Ans:
C
Q.55 In two wattmeter method of power measurement, if one of the wattmeter shows zero reading, then it can be concluded that
(A) Power factor is unity (B) Power factor is zero
(C) Power factor is 0.5 lagging (D) Power factor is 0.5 leading
Ans:
C
Q.56 Which of the following will remain the same in all parts of a series circuit?
(A) Voltage (B) Current
(C) Power (D) Resistance
Ans:
B
Q.57 Which single phase motor would you select for a tape recorder?
(A) Reluctance motor (B) Hysteresis motor
(C) Synchronous motor (D) Universal motor
Ans:
B
Q.58 Under the condition of resonance, RLC series circuit behaves as a,
(A) Purely resistive circuit. (B) Purely inductive circuit.
(C) Capacitive circuit. (D) Reactive
circuit.
Ans:A
Q.59 During
charging, the electrolyte of a lead acid cell becomes
(A) Stronger. (B) Weaker.
(C) Water. (D)
Diluted.
Ans:D
Q.60 As compared to shunt and compound motors, series motor have the highest torque because of its comparatively __________ at the start.
(A) Lower armature resistance. (B) Stronger series field.
(C) Fewer series turns. (D) Larger armature current.
Ans:D
Q.61 The input of an ac circuit having p.f. of 0.8 lagging is 20 kVA. The power drawn by the circuit is __________ kW.
(A)
12. (B) 20.
(C) 16. (D) 8.
Ans: C
Q.62 The voltage ratio of the transformer is given as
(A) 
(B) 
(C) 
(D)
Ans:A
Q.63 The relationship between the frequency of ac wave and the time period is given by
(A) f = T (B) 
(C) 
(D)
Ans: C
Q.64 Which of the following power plant has the maximum efficiency?
(A) Thermal (B)
Hydroelectric
(C) Nuclear (D)
Diesel
Ans:C
Q.65 Three capacitors of
value 
, 
and 32
are connected in series, the total capacitance will be
(A) 
. (B)
7.32 .
(C)
56 . (D)
32 .
Ans: A
Q.66 The following components are all active
components
(A)
a resistor and an inductor.
(B)
a diode, a BJT and an FET.
(C)
a capacitor, and an inductor.
(D)
an Opamp, a BJT and thermionic triode.
Ans: B
Q.67 In
forward mode NPN BJT, if we increase the voltage 
, the collector current increases
(A)
due to ohm’s law, higher causes higher
current.
(B)
due to base width decrease less carrier recombine in the
base region.
(C)
as the gradient of the minority carriers in the base region
becomes steeper.
(D)
due to both the reasons (B) and (C).
Ans: D
Q.68 The
barrier voltage 
in a junction
diode is the effect of
(A)
the p-side and n-side of the junction forming a battery.
(B)
the emf required to move the holes fast enough to have the
mobility equal to that of the electrons.
(C)
the recombination of charge carriers across the junction
leaving behind the opposite charged ions.
(D) the voltage needed to
make the semiconductor material behave as a conductor.
Ans:C
Q.69 An emitter follower has high
input impedance because
(A)
large emitter resistance is used.
(B)
large biasing resistance is used.
(C)
there is negative feedback in the base emitter circuit.
(D)
the emitter-base junction is highly reverse biased.
Ans: C
Q.70 In a differential
amplifier an ideal CMRR is
(A) infinity. (B)
zero.
(C) –1. (D)
+1.
Ans: A
Q.71 FET is advantageous in
comparison with BJT because of
(A) high input impedance. (B)
high gain-bandwidth product.
(C) its current
controlled behaviour. (D) high noise immunity.
Ans: A
Q.72 The emission of electrons in a vacuum
diode is achieved by
(A)
electrostatic field. (B) magnetic field.
(C) heating. (D) electron bombardment.
Ans: C
Q.73 The colour code of a
resistor of nominal value 
10% is
(A) Red, violet, red and silver. (B) Red, violet, yellow and gold.
(C)
Red, violet, orange
and silver. (D) Red, violet, red and gold.
Ans: A
Q.74 Capacitor that can have the highest capacitance value is
(A)
Mica (B) Paper
(C) Electrolytic (D) Ceramic
Ans: C
Q.75 The equivalent current-source representation for a voltage-source with open circuit voltage 12 V and internal resistance 3 ohms is
(A) a current-source of strength 4A in shunt
with a resistance of 
.
(B) a current –source of
strength 4A in series with a resistance of 
.
(C) a current-source of
strength 4A in shunt with a resistance of 3 ohms.
(D) a current-source of strength 4A in shunt with a resistance
of 36 ohms.
Ans: C
Q.76 An intrinsic semiconductor at absolute zero temperature
(A) has a large number of holes.
(B)
behaves like an insulator.
(C)
behaves like a metallic conductor.
(D)
has few holes and same number of electrons.
Ans:
A
Q.77 The
current flow through a Ge PN junction diode with a forward bias of 0.22 Volt
and a reverse saturation current of 1 mA at 
is around
(A)
6.3 A (B) 5.22 A
(C) 4 mA (D) 5.1 mA
Ans: B
Q.78 For the operation of a depletion-type N-MOSFET, the gate voltage has to be
(A)
low positive (B) high positive
(C) high negative (D) zero
Ans: D
Q.79 The typical operating voltage for LED’s ranges from
(A)
0.2 V to 0.6 V. (B) 6 V to 10 V.
(C) 1.5 V to 2.5 V. (D) 9 V to 10 V.
Ans: C
Q.80 Capacitors for integrated circuits
(A)
cannot be made using diffusion techniques.
(B)
can be made with very high values of capacitance.
(C)
are always discrete components connected externally.
(D)
can be made using silicon dioxide as the dielectric.
Ans: D
Q.81 The magnitude of variation in the output voltage for a 10 V regulated dc power supply of 0.002% regulation will be
(A) 0.2 mV. (B)
0.002 mV.
(C) 0.02 mV. (D) 0.2
.
Ans: A
Q.82 For the circuit shown in Fig.1, the output voltage is given by
(A) 
.
(B) 
.
(C) 
.
(D) 
.
Ans: C
Q.83 Which one of the
following statements is not true?
(A) Capacitance is a measure of a capacitor’s
capability to store charge.
(B)
A capacitor offers high impedance to ac but
very low impedance to dc.
(C) A capacitor is also
used as bypass capacitor.
(D)
Capacitors are used to couple alternating
voltages from one circuit to another and at the same time to block dc voltage
from reaching the next circuit.
Ans:
B
Q.84 A voltage source having an open-circuit voltage of 100 V and
internal resistance of 50
is equivalent to a current source
(A) 2A in parallel with 50. (B)
2A with 50 in series.
(C) 0.5A in parallel with
50. (D)
2A in parallel with 100.
Ans: A
Q.85 In a Zener diode large reverse current is due to
(A)
collision. (B)
presence of impurities.
(C) rupture of bonds (D)
lower resistance in reverse biased
region.
Ans: D
Q.86 Ripple factor of a
full-wave rectifier without filter will be
(A) 0.2. (B)
0.48.
(C) 0.24. (D) 1.21.
Ans: B
Q.87 JFET has main drawback of
(A)
having low input impedance.
(B)
having high output impedance.
(C)
being noisy.
(D)
Having small gain-bandwidth product.
Ans: D
Q.88 A
UJT has
(A) stable negative
resistance characteristics.
(B)
low firing current.
(C)
use as a waveform generator.
(D)
all of these characteristics.
Ans: D
Q.89 For thermionic emission
(A) a material with high
work function is preferable.
(B)
a material with low work function is preferable.
(C)
the work function of the material has no importance.
(D)
None of these is true.
Ans: B
Q.90 Ideal operational amplifier has input impedance of
(A) 
. (B) infinity.
(C) zero. (D) 
.
Ans: B
Q.91 The CE configuration amplifier circuits are preferred over CB configuration amplifier circuits because they have
(A) lower amplification factor.
(B) Larger amplification factor.
(C) high input resistance
and low output resistance.
(D) none of these.
Ans: B
Q.92 The most commonly used type of electron emission in electron tubes
is
(A) Photo-electron emission. (B) Thermionic emission.
(C) Field emission. (D) Secondary emission.
Ans: A
Q.93 The colour band sequence of a
resistor is grey, Blue, gold, and gold.
The range in which its value must lie so as to satisfy the tolerance
specified is between
(A) 
and 
(B) 
and 
(C) 
and 
(D) 
and 
Ans: D
Q.94 A device whose characteristics are very close to that of an ideal
current source is
(A) a gas diode. (B)
a BJT in CB mode.
(C) a BJT in CE mode. (D) a triode.
Ans: C
Q.95 In
an N-type semiconductor, the concentration of minority carriers mainly depends
upon
(A) the doping technique. (B)
the number of donor atoms.
(C) the temperature of the material (D) the quality of the intrinsic material,
Ge or Si.
Ans: B
Q.96 When
forward bias is applied to a junction diode, it
(A) increases the
potential barrier.
(B) decreases the
potential barrier.
(C) reduces the majority-carrier current to zero.
(D) reduces the minority-carrier current to zero.
Ans: B
Q.97 The theoretical maximum efficiency of a Bridge rectifier circuit is
(A) 48.2%. (B) 81.2%.
(C) 82%. (D) 40.6%.
Ans: B
Q.98 The
input resistance of a common-collector configuration will be of the order
of
(A) 
(B) 
(C) 
(D) 
and above
Ans: D
Q.99 A switching voltage regulator can be of the following type:
(A) step-down (B) step-up
(C) inverting (D) none of these
Ans: A
Q.100 A UJT contains
(A) four pn junctions (B) three pn junctions
(C) two pn junctions (D) one pn
junction
Ans: D
Q.101 The foundation on which an IC is built is called
(A) an insulator. (B) a base.
(C) a wafer. (D) a
plate.
Ans: C
Q.102 X-ray tubes make
use of
(A) Thermionic emission.
(B) Secondary emission.
(C) High field emission. (D) Photoelectric
emission.
Ans: C
Q.103 Which of the
following components are all active components?
(A) A resistor and a capacitor.
(B) A microphone, a LCD and a Thyratron.
(C) An electric bulb, a
transformer and a varactor diode.
(D) An SCR, a vacuum
diode and an LED.
Ans: D
Q.104 Doping materials are called impurities because they
(A)
Decrease the number of charge carriers.
(B) Change the chemical
properties of semiconductors.
(C)
Make semiconductors less than 100 percent pure.
(D)
Alter the crystal structures of the pure semiconductors.
Ans: B
Q.105 Avalanche breakdown is primarily dependent on the phenomenon of
(A) Collision (B) Doping
(C) Ionisation (D) Recombination
Ans: D
Q.106 In a rectifier, larger the value of shunt capacitor filter
(A) Larger the
peak-to-peak value of ripple voltage.
(B)
Larger the peak
current in the rectifying diode.
(C) Longer the time that current pulse flows through
the diode.
(D) Smaller the dc voltage across the load.
Ans: D
Q.107 The main reason why electrons can tunnel through a P-N junction is that
(A) They have high
energy.
(B) Barrier potential is
very low.
(C)
Depletion layer is extremely thin.
(D)
Impurity level is low.
Ans:
C
Q.108 If a change in base current does not change the collector current, the transistor amplifier is said to be
(A) Saturated. (B) Cut-off.
(C) Critical. (D) Complemented.
Ans: A
Q.109 The extremely high input impedance of a MOSFET is primarily due to the
(A) Absence of its
channel.
(B) Negative gate-source
voltage.
(C) Depletion of current
carriers.
(D) Extremely small
leakage current of its gate capacitor.
Ans: A
Q.110 After firing an SCR, the gating pulse is removed. The current in the SCR will
(A) Remains the same. (B) Immediately fall to zero.
(C) Rise up. (D) Rise a little and then fall to zero.
Ans: A
Q.111 An
inverting operational amplifier has 
and 
. Its scale
factor is
(A) 1000. (B) 
.
(C) 
. (D) 
.
Ans: B
Q.112 In the context of IC
fabrication, metallisation means
(A) Connecting metallic wires.
(B) Forming
interconnecting conduction pattern and bonding pads.
(C) Depositing 
layer.
(D) Covering with a
metallic cap.
Ans: B
Q.113 The colour band sequence of a resistor is yellow, violet,
orange and gold. The range in which its
value must lie so as to satisfy the tolerance specified is between
(A) 
and 
(B) 
and 
(C) 
and 
(D) 
and 
Ans: D
Q.114 A device whose characteristics are very close to that of an ideal voltage source is
(A) a vaccum diode. (B) a DIAC.
(C) a zener diode. (D) a FET.
Ans: C
Q.115 The forbidden energy gap in semiconductors
(A) lies just below the
valance band
(B) lies just above the
conduction band
(C) lies between the
valence band and the conduction band
(D) is the same as the
valence band
Ans: C
Q.116 The barrier potential for a Ge PN junction is
(A) 0.6V. (B) 0.3V.
(C) 0.1V. (D) 0.5V.
Ans: B
Q.117 The ripple factor of a power supply is a measure of
(A) its voltage regulation. (B) its diode rating.
(C) purity of power output. (D) its filter efficiency.
Ans: C
Q.118 In a BJT, if the emitter junction is reverse-biased and the collector junction is reverse-biased, it is said to operate in
(A)
in active region (B) in saturation region
(C) in cut-off region (D)
none of the above
Ans: C
Q.119 In the switching type of voltage regulators, the power efficiency will be of the order of
(A) 50% or less. (B) 60%.
(C) 40% or more. (D) 90% or more.
Ans: D
Q.120 The resistance between bases of a UJT is typically in the range of
(A) 
(B)
(C) 15 to 20 K (D) 18 to 20 K
Ans: B
Q.121 The quantity that serves as a figure of merit for a DIFF AMP is
(A) slew rate. (B) bandwidth.
(C) input bias current. (D) CMRR.
Ans: D
Q.122 Practical range of
resistance values obtainable with base diffused resistors is
(A) 10 to 1 K (B) 20 to 30 K
(C) 5 to 3 K (D) 20K to 50 K
Ans: D
Q.123 The colour band sequence of a resistor is Yellow, Violet,
(A) 
and 
(B) 
and 
(C) 
and 
(D) 
and 
Ans:
B
Q.124 With increasing temperature, the resistivity of an intrinsic
semiconductor decreases. This is because, with the increase of temperature
(A)
The carrier concentration increases but the mobility of
carriers decreases.
(B) Both the carrier
concentration and mobility of carriers decreases.
(C) The carrier concentration decreases, but the mobility of carriers increases.
(D) The carrier concentration remains the same but the mobility of carriers
decreases.
Ans: A
Q.125 At room temperature of 25şC, the barrier Potential for Silicon is 0.7V. Its value at 0şC will be
(A) 0.7 V. (B) 0.65 V.
(C) 0.75 V. (D) 0.55 V.
Ans: C
Q.126 Which
of the following is a unipolar device?
(A) P-N junction diode (B) Zener diode
(C) Tunnel diode (D) Schottky diode
Ans: D
Q.127 On applying a Positive voltage signal to the base of a normally biased N-P-N CE transistor amplifier
(A) Base current will
fall.
(B) Collector current will fall.
(C) Emitter current will fall.
(D) Collector voltage will become less positive.
Ans: D
Q.128 An N-channel JFET has Pinch-off Voltage of VP = – 4V and given that VGS = –1V, then the minimum VDS for the device to operate in the Pinch-off region will be
(A) +1V (B) +3V
(C) +4V (D) +5V
Ans: B
Q.129 The extremely high input impedance of a MOSFET is Primarily because of
(A) Absence of its channel
(B) Depletion of current carriers
(C) Extremely small
leakage current of its gate capacitor
(D) Negative VGS
Ans: A
Q.130 When two identical SCRs are placed back-to-back in series with a load and if each is fired at 90ş, then the voltage across the load will be
(A) 
(B) Zero
(C) 
(D) 
Ans: A
Q.131 
In the
differentiating circuit shown in Fig.1, the function of resistor R1
is to
(A)
Enable the circuit to approach ideal differentiator
(B) Maintain high input
impedance
(C) Eliminate high
frequency noise spikes
(D) Prevent oscillations
at high frequencies
Ans:C
