問題一覧
1
Which of the following statements are TRUE?
An ideal voltage source can be in parallel with an open circuit
2
What is the heating process makes use of of the currents induced by the electromagnetic action in the charge to be heated used for hardening of steel.
Induction heating
3
The best place to install a capacitor is
across the terminals of the inductive load
4
The inverse capacitance is called
Elastance
5
"In any linear bilateral network, if a source of emf E in any branch produces a current I in any other branch, then the same emf acting in second branch would produce the same current I in the first branch". the statement above is associated with.
reciprocity theorem
6
All definition of power factor of a series R-L-C circuit is correcct except
ratio of net reactance and impedance
7
In a star connected system, the line current is
equal to the phase current
8
The magnetic torque exrted on a flat current-carrying loop of wire by a uniform magnetic field "B" is?
maximum when the plane of the loop is parallel to "B"
9
What is the form factor of half wave rectified sinusoidal wave
1.57
10
Permitivity is expressed in
Farad/meter
11
When the frequency of oscillator in a series RLC circuit is doubled
the capacitance reactance is halved
12
Which of the following materials has the highest value of dielectric constant?
ceramics
13
Electric pressure in an electric circuit iis alse called
voltage
14
out of the following, select the best conductor of electricity
Graphite
15
The unit of relative permeability is
It is dimensionless
16
In three phase wye connected balanced voltage system, the angle between line voltage and phase voltage is _____ degrees
30
17
What is the watt-hour efficiency of storage battery?
WH output based on WH input recharge
18
How many erg per second are there in one watt
10 exp 7
19
The voltage of domestic supply is 220V. this figure represents
rms value
20
In series R-L circuit, the power factor cannot be greater than ______ and or cannot be less than _______
(1,0)
21
The power angle of a balanced 3-phase load is the phase angle between
phase voltage and phase current
22
The two windings of a transformer is
inductively linked
23
In delta connected system, the line current is
1.732 times the phase current
24
For measuring the resistance of the elements of an attenuator which of the following is the best choice
Wheatstone bridge
25
The unit of magnetic dipole moment are
ampere-meter^2
26
For the same peak value which of the following wave will have the highest rms value?
square wave
27
What is the minimum number of wattmeter/s required for measuring power of a three phase balanced load
one
28
The coulumb force, F, acts on two charges a distance, r, appart. What is F proportional to?
1/r^2
29
The direction of induced e.m.f can be found by
Lenz's law
30
2 resitors are connected in parallel across a potential difference. The resistance of resistor "A" is twice as resistor "B". If the current carrie by resistor "A" is I, then what is the current carried by resistor B?
2 I
31
If an electrical network having one or more voltage source, is transformed into equivalent electrical network with single voltage source (which is short circuit current of previous circuit) with parallel internal resistance of the network with all current source replaced by their internal resistance. The above illustration is called
Northon's theorem
32
In a circuit containing R, L and C, powerloss can take place in
R only
33
What will happen if a lead-acid battery is kept in dischared for a long time?
the plates will become sulphated
34
12 resistance 1 ohm each are arranged along the edge of a cube with junctions at corners. What resistance will be measured between terminals of symmetrically opposite corners of the cube
5/6-ohm
35
In an AC circuit, a low value of kVAR compared with kW indicates
high power factor
36
The resistance of resistor 1 is twice of resistor 2. The two are connected inin series and a potential difference is maintained across the combination. what is the rate of thermal energy generation in resistor 1?
twice that in resistor 2
37
Which of the following circuit component opposes the change in the circuit voltage
capacitance
38
Which of the following can be used to measure small dc generated voltages?
Galvanometer
39
For which of hte following parameter variation the capacitance of the capacitor remains unaffected?
Thickness of the plates
40
The quality fctor of R-L-C circuit will increase if
R decreases
41
In a pure inductive circuit if the supply frequency is reduced to 1/2, the current will
be doubled
42
In a series resonant circuit, the current of the circuit is
maximum
43
What is the minimum number of wattmeter required to measure unbalanced power of a three phase system
two
44
the unit of magnetic flux is the same as that of?
pole strenght
45
In a balanced three phase star connected system, the line voltage is
the phasor difference of two phase voltages
46
It was experimentally found by James Prescott that the heat produced in a current carrying conductor is proportional to
I^2
47
In a three-phase supply floating neutral is undesirable because it give way to
unequal line voltages across the load
48
What is the rms value of an AC current?
The steady current that prduces the same rate of heating a resistor as the acual current
49
Permeability in a magnetic circuit corresponds to _______ in an elctric circuit.
conductivity
50
What will happen to an insulating meduim with voltage more than breakdown voltage is applied
It will get punctured
51
A substance or material having relative permeability of less than unity is classified as:
dia-magnetic
52
The voltage applied accross the resistor was reduced by 50%. The power consumed is reduced by?
75%
53
In electromagnetic induction three of the following terms are identical. Name the ONE that is NOT
flux
54
Over charging of lead acid battery is likely to result in
sedimentation
55
The presence of electric current is only made known by the effect it produces. Three important effect are:
heating, magnetic and electric shock
56
In a balance 3-phase wye connected generator, the line to line voltage is
1.732 times the phase the voltage
57
What is the other terms for american wire gauge?
brown and sharpe
58
In a purely inductive circuit
actual power is zero
59
A cylindrical copper rod has a resistnce R. It is reformed to twice its original length with no change in volume. What is the new resistance?
4R
60
The rms value and mean value is the same in the case of
square wave
61
The ratio of the bandwidth to the resonance frequency is called the _____ of the circuit
selectivity
62
Two resistance R1 and R2 are connected in series across the voltage source where R2>R1. The largest drop will be across
R2
63
Which of the following statement is true both for series and parallel DC circuit?
power are additive
64
In a star connected system, the line current is
equal to the phase current
65
The r.m.s value of the sine wave is equal to
0.707 max value
66
An emf induced by changing of current in the neighboring coiled is called:
mutually induced
67
A series R-L-C circuit draws current at leading power factor at
less than resonant frequency
68
The least number of 1-phase wattmeter required to measure the total power consumed by an unbalance load fed from 3-phase 4-wire system
three
69
For an unbalanced load, which connection is suitable
4-wire star connection
70
Suppose that the fundamental dimension are taken to be force (F), velocity (V) and time (T). What ar the dimension of potential energy?
FVT
71
which statement about a charge placed on a dielectric material is true?
The charge is confined to the region in which the charge was placed
72
Two wires of the same material have the same lengths but different diameters. They are connected in series to a battery. Which of the following quantity is the same for the two wires?
current
73
In the case of an unsymmetrical alternating current the average value must always be taken over
the whole cycle
74
In two wattmeter method, the readings of the wattmeter will be identical when
power factor is unity
75
A wattmeter is installed in a balanced 3-phase system with current coil at line a while voltage coil accross B and C. The wattmeter will measure
reactive power
76
In pure resistive circuit
current is in phase with the voltage
77
A resistor with a resistance R1 and a resistort with a resistance of R2 are connected in parallel to an ideal battery with emf V. What is the rate of thermal energy generation in the resistor with a resistance of R1?
V^2/R1
78
What is the basis for declaring the direction of electric current is from positive terminal to negative terminal of a circuit?
Conventional
79
A salient pole synchronous motor is running at no load. Its field current is switched off. The motor will
continue to run at synchronous speed
80
The ratio of active power to apparent power is known as __________ factor
power
81
Which of the following statements is TRUE for steady-state conditions in a circuit powered by a dry cell?
Inductors behave as short circuit
82
In flemming's right hand rule, which finger point the direction of current?
Middle
83
When the phase sequence at the three phase load is reversed
phase current are changed in angle but not in magnitude
84
In an series resonant circcuit, the impedance of the circuit is
minimum
85
An LC series circuit with an inductance L and a capacitor C has an oscillation frequency of f. Two inductors, each with inductance L, and two capacitors, each with capacitance C, are all wired in series and the circuit is completed, the oscillation frequency is _________.
f
86
A pure inductance connected across 250 V, 50 Hz supply consumes 100 W. this consumption can attributed to
the statement given is false
87
The voltage of domestic supply is 220 V. This figure represents
rms value
88
In a balanced 3-phase voltage generato, the different phase voltages are _______ degrees appart
120
89
In American Wire Gauge (AWG) as the number gauge increases the wire diameter?
decreases
90
The period of the wave
Time required to complete one cycle
91
In pure inductive circuit, the current lags the voltage by
one fourth of the cycle
92
The positive phase sequence of a three pahse load is abc, the negative sequence would not be
cab
93
Which of the following coductors has the highest resistance?
Nichrome
94
Superposition theorem can be applied only to circuits having
linear bilateral elements
95
The type of ac distribution system commonly used to supply both light and power is the
three phase star system with neutral wire
96
Which of the following will the effect of the electric shock in the human body depends on
current flowing in the body
97
Kirchoff's law is not applicable to circuit with
distributed parameters
98
in a series resosnant circuit the voltage across the ciruit is the same as the voltage across the
resistance
99
The power is to be measured for a balanced delta connected load whose terminals cannot be opened. How many wattmeters do you need?
two
100
Which of the following AC device is used to measure the angle between the voltage and its current
phase angle meter