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Free download in PDF Circuit Theory Objective Type Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
(21)
The time constant of the capacitance circuit is defined as the time during which voltage
[A]
falls to 36.8% of its final steady value
[B]
rises to 38.6% of its final steady value
[C]
rises to 63.2% of its final steady value
[D]
none of the above
Answer: rises to 63.2% of its final steady value
(22)
Power factor of the system is kept high
[A]
to reduce line losses
[B]
to maximise the utilization of the capacities of generators, lines and transformers
[C]
to reduce voltage regulation of the line
[D]
due to all above reasons
Answer: due to all above reasons
(23)
Power factor of the following circuit will be unity
[A]
inductance
[B]
capacitance
[C]
resistance
[D]
none of these
(24)
Power factor of the following circuit will be zero
[A]
resistance
[B]
inductance
[C]
capacitance
[D]
both (b) and (c)
(25)
In a highly capacitive circuit the
[A]
apparent power is equal to the actual power
[B]
reactive power is more than the apparent power
[C]
reactive power is more than the actual power
[D]
actual power is more than its reactive power
Answer: reactive power is more than the actual power
(26)
Power factor of an inductive circuit is usually improved by connecting capacitor to it in
[A]
parallel
[B]
series
[C]
either (a) or (b)
[D]
none of the above
(27)
Time constant of an inductive circuit
[A]
increases with decrease of inductance and increase of resistance
[B]
increases with decrease of inductance and decrease of resistance
[C]
increases with increase of inductance and decrease of resistance
[D]
increases with the increase of inductance and the increase of resistance
Answer: increases with increase of inductance and decrease of resistance
(28)
All the rules and laws of D.C. circuit also apply to A.C. circuit containing
[A]
capacitance only
[B]
inductance only
[C]
resistance only
[D]
all above
(29)
Inductance affects the direct current flow
[A]
only at the time of turning off
[B]
only at the time of turning on
[C]
at the time of turning on and off
[D]
at all the time of operation
Answer: at the time of turning on and off
(30)
Pure inductive circuit
[A]
consumes some power on average
[B]
does not take power at all from a line
[C]
takes power from the line during some part of the cycle and then returns back to it during other part of the cycle
[D]
none of the above
Answer: takes power from the line during some part of the cycle and then returns back to it during other part of the cycle
31
In series resonant circuit, increasing inductance to its twice value and reducing capacitance to its half value
[A]
will change the maximum value of current at resonance
[B]
will change the resonance frequency
[C]
will change the impedance at resonance frequency
[D]
will increase the selectivity of the circuit
Answer: will increase the selectivity of the circuit
32
Capacitors for power factor correction are rated in
[A]
kW
[B]
kVA
[C]
kV
[D]
kVAR
33
Poor power factor
[A]
reduces load handling capability of electrical system
[B]
results in more power losses in the electrical system
[C]
overloads alternators, transformers and distribution lines
[D]
results in all above
Answer: results in all above
34
The best place to install a capacitor is
[A]
very near to inductive load
[B]
across the terminals of the inductive load
[C]
far away from the inductive load
[D]
any where
Answer: across the terminals of the inductive load
35
Power factor of an electrical circuit is equal to
[A]
R/Z
[B]
cosine of phase angle difference be-tween current and voltage
[C]
kW/kVA
[D]
all above
36
In a series resonant circuit, the impedance of the circuit is
[A]
minimum
[B]
maximum
[C]
zero
[D]
none of the above
37
Capacitive reactance is more when
[A]
capacitance is less and frequency of supply is less
[B]
capacitance is less and frequency of supply is more
[C]
capacitance is more and frequency of supply is less
[D]
capacitance is more and frequency of supply is more
Answer: capacitance is less and frequency of supply is less
38
The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of______degrees.
[A]
90
[B]
60
[C]
45
[D]
30
39
The phase difference between voltage and current wave through a circuit element is given as 30°. The essential condition is that
[A]
both waves must have same frequency
[B]
both waves must have identical peak values
[C]
both waves must have zero value at the same time
[D]
none of the above
Answer: both waves must have same frequency
40
Pure inductive circuit takes power from the A.C. line when
[A]
applied voltage decreases but current increases
[B]
applied voltage increases but current decreases
[C]
both applied voltage and current increase
[D]
both applied voltage and current decrease
Answer: applied voltage decreases but current increases
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