c. A 50 Hz, 3-phase induction motor has a full load speed of 1440
r.p.m. The number of poles of the motor are
(A) 4.
(B) 6.
(C) 12.
(D) 8.
d. In a 3-phase synchronous motor
(A) the speed of stator MMF is always more than that of rotor
MMF.
(B) the speed
of stator MMF is always less than that of rotor MMF.
(C) the speed of stator MMF is
synchronous speed while that of rotor MMF is
zero.
(D) rotor and stator MMF are stationary
with respect to each other.
e. In a capacitor start single-phase induction motor, the capacitor
is connected
(A) in series with main
winding.
(B) in series with auxiliary winding.
(C) in series with both the
windings.
(D) in parallel with auxiliary
winding.
f. A synchro has
(A) a 3-phase winding on rotor and a
single-phase winding on stator.
(B) a 3-phase winding on stator and a
commutator winding on rotor.
(C) a 3-phase winding on stator and a
single-phase winding on rotor.
(D) a single-phase winding on stator and
a commutator winding on rotor.
g. As the voltage of transmission increases, the volume of
conductor
(A) increases.
(B) does not change.
(C)
decreases.
(D) increases proportionately.
h. The size of the feeder is determined primarily by
(A) the current it is required to carry.
(B) the
percent variation of voltage in the feeder.
(C) the voltage across the
feeder.
(D) the
distance of transmission.
Q.1 Choose the correct or best alternative in
the following: (2x8)
a.
a. A two-winding single phase transformer has a voltage regulation of
4.5% at full-load and unity power-factor. At full-load and 0.80 power-factor
lagging load the voltage regulation will be
(A) 4.5%. (B)
less than 4.5%.
(C) more than 4.5%. (D) 4.5% or
more than 4.5%.
b.
b. In
a dc shunt motor the terminal voltage is halved while the torque is kept
constant. The resulting approximate variation in speed 
and armature current 
will be
and armature current will be
(A)
(A) Both 
and 
are doubled. (B) is constant and is doubled.
and are doubled. (B) is constant and is doubled.
(C) is doubled
whileis halved. (D) is constant but is halved.
is doubled
whileis halved. (D) is constant but is halved.
c. A balanced three-phase, 50 Hz voltage is
applied to a 3 phase, 4 pole, induction motor. When the motor is delivering
rated output, the slip is found to be 0.05. The speed of the rotor m.m.f.
relative to the rotor structure is
(A) (A)
1500 r.p.m. (B)
1425 r.p.m.
(C) 25 r.p.m. (D) 75 r.p.m.
d. An alternator is delivering rated
current at rated voltage and 0.8 power-factor lagging case. If it is required
to deliver rated current at rated voltage and 0.8 power-factor leading, the
required excitation will be
(A) less. (B)
more.
(C) (C)
more or less. (D)
the same.
e. A ceiling fan
uses
(A)
(A) split-phase motor.
(B)
(B) capacitor start and capacitor run motor.
(C) (C)
universal motor.
(D) (D)
capacitor start motor.
f. A stepper
motor is
(A) (A)
a dc motor. (B)
a single-phase ac motor.
(C) a multi-phase motor. (D) a two
phase motor.
g. The
sheath is used in cable to
(A) provide strength to the cable.
(B) provide proper
insulation.
(C) prevent the
moisture from entering the cable.
(D) avoid chances of
rust on strands.
h. The drive motor used in a mixer-grinder
is a
(A) dc motor. (B) induction motor.
(C) synchronous motor. (D) universal motor.
Q.1 Choose
the correct or best alternative in the following: (2x8)
c. a.
A series RLC circuit
will have unity power factor if operated at a frequency of __________.
(A)
. (B)
.
. (B)
.
(C)
. (D)
.
. (D)
.
d. b. The difference between synchronous
speed and the actual speed of an induction motor is known as ___________.
(A) regulation. (B) back lash.
(C) slip. (D)
lag.
c. The efficiency of a transformer is given as
__________.
(A) output/(output + losses). (B) (output +
losses)/output.
(C) input/output. (D)
(output + losses)/input.
d. Speed of a motor is given by ___________.
(A) 120
f/p. (B)
120 p/f.
(D)
(C)
60f/p. (D) 60
p/f.
e. Load factor is defined as _________.
(E) (A) average demand / maximum demand.
(F)
(B)
average demand /
installed capacity.
(G)
(C)
maximum demand /
average demand.
(H)
(D)
maximum demand /
installed capacity.
f. Like a resonant R-L-C circuit, a parallel
resonance circuit also _________.
(B)
(A)
has a power factor
of unity. (B) offers minimum
impedance.
(C) draws maximum current. (D) magnifies current.
g. Slip rings for an induction motors are made
of
(A) Aluminium. (B)
Carbon.
(C) Phosphor bronze. (D) Cobalt steel.
h. The motor which has the least noise is the
________.
(A) capacitor
motor. (B) universal
motor.
(C) shaded
pole motor. (D) hysteresis
motor
Q.1
Choose the correct or best alternative in the
following:
(2x8)
a.
The “Superposition
theorem” is essentially based on the concept of
(A)
duality.
(B) linearity.
(C)
reciprocity.
(D) non-linearity.
b.
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.
c. The power factor of a purely resistive circuit is
(A) zero.
(B) unity.
(C) lagging.
(D) leading.
d. The power taken by a 3-phase load is given by the expression
(A) 
.
(B) 
.
.
(B) .
(C) 
.
(D) 
.
.
(D) .
e. 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.
f. Which of the following motors has a high starting torque?
(A) ac series
motor.
(B) dc series motor.
(C) induction
motor.
(D) synchronous motor.
g. A step-up transformer increases
(A) voltage.
(B) current.
(C)
power.
(D) frequency.
h. 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.
a.
A set of readings has
wide range and therefore it has:
(A) Low precision
(B) High precision
(C) Low
accuracy
(D) High accuracy
b.
Thermocouple
instruments can be used for a frequency range:
(A) up to 100
Hz
(B) up to 5000 Hz
(C) up to 1
Hz
(D) 50 MHz and above
c. Electrostatic type instruments are primarily used as :
(A) Ammeter
(B) Watt meter
(C)
Voltmeter
(D) Ohmmeter
d.
Frequency can be measured by using:
(A) Maxwell’s
bridge
(B) Schering’s bridge
(C) Hay’s
bridge
(D) Wien’s bridge
e. An aquadag is used in a CRO to collect:
(A) Primary
electrons
(B) Secondary emission electrons
(C) Both primary and
secondary (D) None
of the above
emission electrons
f. The Q factor of a coil at the resonant frequency of an RLC
series circuit is 150. The bandwidth is :
(A) 225
MHz
(B) 1.06 MHz
(C) 10
KHz
(D) None of the aove
g. Piezo electric transducers are:
(A) Passive
transducers
(B) Active transducers.
(C) Inverse
transducers.
(D) (B) and (C).
h. If a transducer has an output impedance of 
and a load resistance of , it behaves as :
and a load resistance of , it behaves as :
(A) a constant current
source
(B) a constant voltage source
(C) a constant
impedance.
(D) none of the above
i. For a radio receiver, its sensitivity indicates:
(A) a response which is
spurious
(B) the ability to reject an
unwanted signed
(C) the measure of noise
produced
(D) the receiver’s ability to pick up weak signal
j. An 8 bit converter is used for a d.c. range of 0-10 V. Find the weight
of LSB
(A) 39
mV
(B) 78 mV
(C) 39.2
mV
(D) None of the above