Question #1
The main advantages of a.c. is ??.
A A.C. motors are
expensive
B The A.C. voltage
can’t be raised or lowered
C A.C. transmission is
very costly
D None
Correct Answer is Option D : None
Question #2
The main advantage of purely sinusoidal waveform is??.
A it is only
alteranating waveform
B it is the only
standard waveform.
C any other waveform
can be resolved into series of sinusoidal waveforms of different frequency
D it produces distorted
waveforms when applied.
Correct Answer is Option C : any other
waveform can be resolved into series of sinusoidal waveforms of different
frequency
Question #3
The waveforms in which magnitude changes but its direction remain same is
called ?
A pulsating d.c.
B alternating
C pure d.c.
D None
Correct Answer is Option A : pulsating
d.c.
Question #4
??. Is the advantage of a.c.
A the voltage can be
raised or lowered
B A.C. transmission is
economical and efficient.
C A.C.can easily
converted to D.C.
D All of the above.
Correct Answer is Option D : All of the
above.
Question #5
The generation of the a.c. is according to ??.
A Faradays law
B Thevenins theorem
C Ohms law
D Kirchhoffs law
Correct Answer is Option A : Faradays law
Question #6
??..represents maximum value of alternating emf
A B I l
B B v l
C B I v
D l I v
Correct Answer is Option A : B I l
Question #7
Standard alternating emf is represented as??.
A Em tan_
B Em cos_
C Em sin_
D None
Correct Answer is Option C : Em sin_
Question #8
Standard alternating emf achieves its positive maximum value at _=??.
A 45
B 90
C 180
D 270
Correct Answer is Option B : 90
Question #9
The time taken by an alternating quantity to complete one cycle is called??.
A Frequency
B Speed
C Waveform
D Time period
Correct Answer is Option D : Time period
Question #10
The unit of frequency is ____
A Rad/sec
B Sec
C Hz
D Volts
Correct Answer is Option C : Hz
Question #11
The relation between f and w is????
A f=1/w
B w=2?/f
C w=2?f
D w=1/f
Correct Answer is Option C : w=2?f
Question #12
The time period of sinusoidal waveform with 200Hz frequency is??..
A 0.005s
B 0.0005s
C 0.5s
D None
Correct Answer is Option C : 0.5s
Question #13
The value of a alternating quantity of a particular instant is called??..value.
A Instantaneous
B Peak
C Peak to peak
D Average
Correct Answer is Option A : Instantaneous
Question #14
The waveform which shows repetation of variations after a regular time interval
is called???
A Nonperiodic waveform
B Sawtooth waveform
C Periodic waveform
D Triangular waveform
Correct Answer is Option C : Periodic
waveform
Question #15
In our nation, the standard frequency of alternating voltage is????.
A 60 cycle/sec
B 50 cycle/sec
C 100 cycle/sec
D None
Correct Answer is Option B : 50 cycle/sec
Question #16
The higher value attained by an alternating quantity during positive or
negative half cycle is called???..
A Maximum
B Amplitude
C Peak
D All
Correct Answer is Option B : Amplitude
Question #17
For 50Hz alternating waveform the angular frequency is?????.rad/sec
A 314.16
B 50
C 0.126
D None
Correct Answer is Option A : 314.16
Question #18
An a.c voltage is given by v=40 sin 314t. The frequency is?????..
A 75Hz
B 50Hz
C 25Hz
D 100Hz
Correct Answer is Option B : 50Hz
Question #19
An alternating voltage is given by v =100 sin (3.14 t-300) volts. The frequency
is ????
A 25Hz
B 50Hz
C 60Hz
D 100Hz
Correct Answer is Option B : 50Hz
Question #20
An A.C. voltage is given by 100 sin 314 t. the frequency is????
A 50Hz
B 75Hz
C 25Hz
D 100Hz
Correct Answer is Option B : 75Hz
Question #21
The equation of an alternating quantity is v = 282.84 sin 100 ? t then its
r.m.s value is???..
A 200
B 20
C 141.421
D 400
Correct Answer is Option A : 200
Question #22
The voltage of domestic a.c. supply is 230V. This value represent???.
A Peak value
B r.m.s. value
C Average value
D Mean value
Correct Answer is Option B : r.m.s. value
Question #23
The voltmeter in a.c. circuit always measures????.values.
A Average
B Maximum
C r.m.s.
D None
Correct Answer is Option A : Average
Question #24
The r.m.s value of an alternating current is 10A then its peak to peak value is
____
A 10A
B 30A
C 5A
D 20A
Correct Answer is Option C : 5A
Question #25
A sinusoidal voltage is represented as 141.42 sin 314 _t then its r.m.s value
of the voltage and frequency are respectively????
A 141.42V, 314Hz
B 100V, 50Hz
C 100V, 60Hz
D 200V, 100Hz
Correct Answer is Option B : 100V, 50Hz
Question #26
The peak value of an alternating current is Im then its average value is????.
A 0.637 Im
B 4.12 Im
C 1.44 Im
D None
Correct Answer is Option A : 0.637 Im
Question #27
The average value of sinusoidal varying voltage is ?.. than its rms value.
A more
B less
C same as
D None
Correct Answer is Option A : more
Question #28
The form factor of purely sinusoidal waveform is ?..
A 1.11
B 1.21
C 1.414
D None
Correct Answer is Option A : 1.11
Question #29
The peak factor of a sinusoidally varying voltage is ??..
A 1.414
B 1.11
C 0.866
D 0.707
Correct Answer is Option B : 1.11
Question #30
Alternating quantities are represented by
A Vectors
B Scalars
C Phasors
D Graphs
Correct Answer is Option C : Phasors
Question #31
Phasors always rotate in________ direction
A Clockwise
B Anticlockwise
C Vertical
D Horizontal
Correct Answer is Option B : Anticlockwise
Question #32
_________ projection of a phasor reprents an instantaneous value of an
alternating quantity
A Y-axis
B X-axis
C Z-axis
D None
Correct Answer is Option B : X-axis
Question #33
The phase of an alternating quantity varies from
A 0-90
B 0-180
C 0-360
D 180-360
Correct Answer is Option C : 0-360
Question #34
When two alternating quantities are in phase then their phase difference
is________
A 30
B 90
C 0
D 60
Correct Answer is Option C : 0
Question #35
The negative maximum of a cosine wave occurs at ???.
A 45
B 90
C 180
D 270
Correct Answer is Option C : 180
Question #36
?????.. representation gives rms value of an alternating quantity
A Phasor
B Polar
C Rectangular
D None
Correct Answer is Option A : Phasor
Question #37
The polar form of -3+j4 is???..
A 5<-53.13
B 5<53.13
C 5<-126.86
D 5<126.86
Correct Answer is Option D : 5<126.86
Question #38
The rectangular form of the 5<30 is ???..
A 4.33+j2.5
B 4.33-j2.5
C Can’t say
D None
Correct Answer is Option A : 4.33+j2.5
Question #39
For a 50Hz transformer, the primary turns are 100 and maximum flux in the core
is 0.08Wb then primary side induced emf is?????..
A 1856V
B 1276V
C 1776V
D 7776V
Correct Answer is Option C : 1776V
Question #40
RMS value of the induced emf per turn in transformer is ????
A 4f_m
B 4.44f_m
C 2f_m
D f_m
Correct Answer is Option B : 4.44f_m
Question #41
For transformer the induced emf on primary is 199.8 V with 50 turns at 50 Hz
frequency than the maximum flux in the core is???..
A 79.92mWb
B 18mWb
C 18Wb
D 0.999Wb
Correct Answer is Option B : 18mWb
Question #42
An ideal transformer is the one having?????..
A No losses
B Zero resistance
winding
C Zero leakage flux
D All
Correct Answer is Option D : All
Question #43
For a 10 KVA 2000/200V transformer the half load secondary current is ??..
A 50A
B 5A
C 25A
D 2.5A
Correct Answer is Option C : 25A
Question #44
If any ammeter in the secondary of a 100/10 V ratio reads 10 A ,The current the
primary would be ??..
A 1A
B 2A
C 10A
D 100A
Correct Answer is Option A : 1A
Question #45
The transformer rating is expressed in VA because???..
A on both side it is
constant
B Losses are
independent of load power factor
C The frequency is
constant
D None
Correct Answer is Option B : Losses are
independent of load power factor
Question #46
For 440 V /100V transformer the secondary turns are 16 than the primary turns
are ?????..
A 4
B 64
C 26
D 8
Correct Answer is Option A : 4
Question #47
A transformer having turns ratio is 1:1 is called ???transformer
A Isolation
B Step up
C Step down
D None
Correct Answer is Option A : Isolation
Question #48
A transformer has secondary full load current of 10A and secondary no load
induced emf of 200v then it is KVA rating is???..
A 2000
B 200
C 2
D 20
Correct Answer is Option C : 2
Question #49
A high voltage side is ???..
A Low current, low
impedance side
B High current, low
impedence side
C Low current, high
impedance side
D None
Correct Answer is Option C : Low current,
high impedance side
Question #50
A low voltage side is ???..
A Low current, low
impedance side
B High current, low
impedence side
C Low current, high
impedance side
D None
Correct Answer is Option B : High current,
low impedence side
Question #51
Regulation of transformer is defined as ?..
A rise in terminal
voltage when loaded
B fall in terminal
voltage when loaded
C change in secondary
terminal volatage from no load to full load as a percentage of secondary no
load terminal voltage
D None
Correct Answer is Option C : change in
secondary terminal volatage from no load to full load as a percentage of
secondary no load terminal voltage
Question #52
For the leading power factor loads ,the regulation of transformer is?.
A Positive
B Negative
C Zero
D Unity
Correct Answer is Option B : Negative
Question #53
For better performance of the transformer ,the regulation of the transformer
must be?.
A High
B Infinite
C Very low
D None
Correct Answer is Option C : Very low
Question #54
the voltage regulation of the transformer is zero for ??.load
A Lagging
B Resistive
C Inductive
D Capacitive
Correct Answer is Option B : Resistive
Question #55
If the transformer regulation is positive, ?..load is connected to the
transformer
A Capacitive
B Inductive
C Resistive
D None
Correct Answer is Option B : Inductive
