UNIT-1(introduction
to electrical engineering)
SECTION-I: Multiple choice questions
1. Ohm’s law is applicable to _________ [ d ]
(a) Semiconductors (b) Electrolytes (c) Arc Lamps
(d) None
Explanation: Ohm’s law is not applicable for semiconductors,
electrolytes, arc lamps. Hence answer id (d) none
2. Kirchhoff’s laws are valid for
__________ circuits. [ d ]
(a) Linear (b) Passive time invariant (c) Non
Linear (d) both Linear & Non Linear
Explanation: Kirchoff’s laws are applicable for both
linear and non linear circuits. Answer is (d)
both Linear & Non Linear
3. The capacitance of a parallel plate capacitor is
not affected by _______ [ b ]
(a) Area of Plates (b) Thickness of plates
(c) Separation between plates (d) Nature of
Dielectric.
Explanation: capacitance C=
;
Capacitance depends on nature of
dielectric material(ε),Area of plates (A), distance between plates or separation between
plates (or) thickness of dielectric material(d).capacitance is not depend on thickness of plates hence answer is
(b)
4. The relationship between Electrical energy (
E),Voltage( V) and Charge( Q) is [ c ]
1.
E=Q / V B) E=QV2 C) E=Q x V D) E=
V / Q2
Explanation: we know that v
=> E=Q x V.Hence answer is (c)
5. The curve representing Ohm’s
law is _________ [ b ]
(a) Sine function (b) Linear (c) Parabola (d) Hyperbola
Explanation: Ohm’s law states that at
constant temperature there exists linear relationship between source (voltage)
and response (current).
6.) Resistance of human body is
about _____Ω [ c]
(a) 10 (b) 100 (c) 1K (d) Zero
7).The ratio of voltage and
current in a closed circuit is ________ [ a ]
(a) Remains Constant (b) Varies (c) Increases (d) Falls
8) Identify the passive element
among the following [C]
A.
Voltage source B. current source
C.inductor D. transistor
Explanation: active elements deliver the energy continuously. Examples for active
elements are voltage source, current source, generator, and transistor.
Resistor, inductor, capacitor are passive elements. Answer is (c) inductor
9).How much energy is stored by a
0.05μF capacitor with a voltage of 1000V? [ A]
A.0.025J B.0.05J C.5J D. 100J
Explanation:
At the End
10).Mesh Analysis is based on ……… [B ]
A.
KCL B.KVL C. Both D. None
Explanation: Mesh is nothing but closed loop .in closed loop we will apply
KVl.Hence mesh analysis is based on KVL.
11). The unit of
quantity of electricity is [ B]
(A) Ampere (B) Coulomb (C) Ohm (D) Electron Volt
12) Conductance is the reciprocal of [ c]
(A) Reactance (B) Impedance (C) Resistance (D)
capacitance
Explanation: Resistance=
.unit of conductance is ohm-1 (or) Siemens.answer is ( c) resistance.
13)
Constant Voltage source is __________ [c ]
(a) Active & Bilateral (b) Passive & Bilateral
(c) Active & Unilateral (d) Passive &
Unilateral
Explanation: voltage
source is active element. Voltage source’s voltage value changes with polarity.
Hence constant voltage source is active and unilateral element. Answer is (c)
active and unilateral
14).The relationship between
voltage & current is same for two opposite directions of current in case of
__________ network. [ d]
(a) Active (b) Passive (c) Unilateral (d) Bilateral
Explanation: in bilateral network voltage and current relationship does not changes with
direction of current. Answer is (d) bilateral
15) An Ideal current source has zero ____ [ a]
(a) Internal Conductance (b) Internal resistance (c) Voltage on No load
(d) Ripple.
Explanation: An ideal voltage source has zero internal resistance and an ideal
current source has infinite internal resistance. Ideal current source has infinite
internal resistance means zero conductance.
16).
Kirchhoff’s Laws are applicable to ________
circuits. [c ]
(a) AC (b) DC (c) AC & DC (d) Passive Networks only
17) The resistance of the conductor
depends on the [ d]
A) Cross section area B) Resistivity of the conductor
C) Length D) All the above
Explanation: At the end
18) One Farad is equal to [c ]
A) 1 ohm B) 1 V/C C) 1 C/V D) None of the above
Explanation: C=
, hence
1F=
hence answer is (C).
19) The unit of inductance is [ a]
A) Henry B) V sec / A C) Both D) Farad
Explanation:
unit of resistance is OHM, unit
inductance is Henry, unit capacitance is farad, unit of current is Amp, unit of
voltage is Volts, unit of power is watts, unit of energy is Joule, unit of
resistivity is Ohm-meter, unit of conductance is ohm-1 or Siemens
20) If in a circuit, the voltage is
reduced to half and resistance is doubled, the current will be [c ]
a) 4 Times b) double c) quarter d) half
Explanation: see At the end
21) Kirchoff’s law is applicable to [ c]
a) Ac circuits only b) Dc circuits only c) Both d) passive
networks only
22) The construction for the validity
under ohm’s law is that: [a ]
A) Temperature should remain
constant B) Current should be proportional to voltage
C) Resistance must be wire would type D)All the above
Explanation:
ohm’s law is applicable at only constant temperature
23 .Kirchhoff’s current law is
applicable only to [d ]
a) Electric circuits b) electronic circuits
c) Closed loops in a network d) Junctions in network
24. An electric
current is the __________ [b ]
a) Random movement of electrons in a conductor
b) Movement of free electrons predominately in one direction
c) Pressure difference between two poles d) the power that
causes drift of electrons
25) The charge Q flowing through a conductor carrying current of I
amperes for t seconds is equal to [ a]
(A)It sec. (B)I/t sec. (C)I/t
Amp./Sec. (D) None of these
Explanation: we know
that current I=
=> Q=It sec
26). The curve representing ohm’s law
is [b ]
(A)Sine function (B) linear (C) a parabola (D) a hyperbola
27). _____________ law states that
the sum of the currents entering into any node is equal to the sum of the
currents leaving that node [c ]
A)Kirchoff’s Voltage B) Faradays C) Kirchoff’s Current D) Electromagnetic
Explanation: KCL(Kirchhoff’s
current law) states that the sum of currents entering into any node is equal to
currents leaving that node.KVL(Kirchhoff’s voltage law) states that algebraic
sum branch voltages in a closed loop is always zero at all instants of time.
28). A linear resistor is one which
obeys [c]
(A) Ampere’s Law (B) Lenz’s Law (C)
Ohm’s Law (D) Kirchhoff’s Law
29). the specific resistance is measured in [ a]
(A)Ω-m (B) Ω/m (C)Ω/m (D) Ω/m 32
Explanation: the unit of specific resistance
(resistivity) is ohm-meter (Ω-m)
30). Constant voltage source is [ d]
(A) Active and bilateral (B) passive and bilateral
(C) Passive and unilateral (D)
active and unilateral
31). A pure inductor [d ]
a) Dissipate energy b) stores
energy c) doesn’t dissipate energy d) both b,c
Explanation: pure
inductor internal resistance is zero hence power loss (power dissipation) is
zero and inductor stores energy
32). A capacitor C=5 microfarad.
Calculate stored energy in it if a d.c voltage of 100v is applied across it [ a]
a)0.025J b) 0.0025 J c) 0.25J d)
2.5 J
Explanation: At the end
SECTION-II: Fill in the blanks
1.
The
condition for validity under ohm’s law is that constant
temperature
2.
Capacitance is the property of a circuit
element to oppose sudden
changes in voltage
Explanation:
The property of inductor is it
opposes sudden changes in current and the property of capacitor is it opposes
sudden changes in voltages .the property of resistor is it opposes current
3.
The best
conductor of electricity is
silver
4.
. the property of opposing the
flow of electrons is called as RESISTANCE………..
5.
Inductor
acts as short circuit to DC
Explanation: At the end
6.
Ideal sources is nothing but sources …without…………… losses
7.
The examples for passive elements
are R,L,C
8.
_EMF______________ is the force that causes a current to flow.
9.
Unit of conductance is mho
10.
1 Volt = 1 Joule
per Coulomb
Explanation: V =
=> 1V=
=> 1V=1 Joule per Coulomb
11. The algebraic
sign of an IR drop primarily depends upon the Direction
of flow current
12.The inductor
behaves at steady state as Short circuit
13.Kirchhoff’s
voltage law states that the algebraic sum of all branch voltages
around any closed path in a circuit is always zero at all instants of time.
14. The unit
of capacitance is Farad
14.Capacitance is a measure of
the ability of a capacitor to store an electric charge.
15.The energy
stored in a capacitor is −
16.The capacitor at
steady state behaves like a Open circuit
Explanation: At the end
17.The property of
the material by virtue which it opposes any change in the magnitude or
direction of electric current passing through the conductor is Inductance
18.The voltage a
cross a resistance of ten ohms and 1A current is 10V
Explanation: At the end
UNIT-2:
NETWORK ANALYSIS
1. The
maximum efficiency of power transfer to the load is _____ % [ b ]
(a)
25 (b) 50 (c) 75 (d) 100
2. A Y arrangement of
resistances has each resistance of 3Ω. The equivalent delta arrangement will
have each resistance of values ______________ Ω. [ a ]
(a) 9 (b) 6 (c) 3
(d) 1
3. While
determining RTH in Thevenin’s and Norton’s equivalent _________ [ c ]
(a) Only current
sources are made dead (b) Only voltage sources are made dead
(c) All independent
sources are made dead. (d) All current & voltage sources are made dead.
4. A Circuit having
neither any energy source nor emf source is called the _______ circuit. [
c ]
(a)
Unilateral (b) Bilateral (c) Passive (d) Active
5. If RA =
RB= RC = R in star network, RAB= RBC =RCA = in
its equivalent delta network. [ B ]
A)
R/3 B) 3R C) R D) 2R/3
6. The internal
resistance of an ideal voltage source is [ A
]
A) Zero B)
infinity C)a finite value D)none of the above
7. The maximum
power transfer theorem can be applied [ C ]
A) Only to DC
circuits B) Only to AC circuits C) To both DC &AC circuits D) neither of
the two
8) In Thevenin’s
equivalent circuit resistance is in SERIES with
Thevenin’s voltage source
9. In series
combination C equivalent =(C1C2)/(C1+C2)
10. The voltage and
current relation of an Inductor VL=Ldi/dt
11) If
there are ‘b’ branches & ‘n’ nodes then the number equations will be ____ [
d]
(a) n-1 (b) b (c) b-n (d) b-n+1
12. The number
of independent loops for a network with ‘n’ nodes and ‘b’ branches is
[ C]
A.
n-1
(B). b-n (C).b-n+1 D. independent of number of nodes
13. Three resistances, each are R Ohms, are
connected in delta. Their equivalent star value for each
resistance
is [c ]
(A)R (B) 3R (C)R/3
(D) 2R
14. Two resistors of 12Ω and 4Ω respectively are
connected in series. A short is placed across the combination. The effective
resistance will be [d ]
(A)
4Ω (B) 12Ω (C)16Ω (D)0Ω
15. The value of resistance in delta connection
is 3ohms its equivalent in star connection is [b ]
a)
3 ohms b) 1 ohm c) 3/2 ohms d) 2/3ohms
16. Two Resistances R1 and R2 are connected in
series equivalent resistance is [a ]
a)R1+R2
b) R1-R2 c) R1*R2 d) R1/R2
17. Four resistors, each of resistance R Ω are
available. The minimum resistance of the combination will be [c ]
(A)4
R (B) R (C) R/4 (D)R/8
18. The maximum efficiency of power transfer to
load is [ a]
(A)50
% (B)25% (C) 75% (D)100%
19. The mutual inductance is represented by
symbol [d ]
a)
K b) L and M c) L d) M
20. The theorem which can’t be applied to multiple
source networks is [d ]
a)
Thevenin’s b) Norton’s c) Super position d) Reciprocity
21.
When two resistances are in parallel the equivalent resistance is (R1R2)/(R1+R2)
22.
The power can’t be measured by superposition theorem.
23.
The superposition theorem is applied to any circuit , the dependent voltage
source in that circuit is always active
24.
Superposition is not valid for power responses.
25.
A closed path made by several branches of the network is known as [ b]
A)
Circuit (B) Loop (C) Junction (D) Branch
26.
Superposition theorem can be applied only to _________ networks. [ c]
A)
Linear (B) Non-linear (C) linear bilateral (D) bilateral
27.
The maximum efficiency of power transfer to load is [b ]
A)
25% (B) 50% (C) 75% (D)100%
28.
Three capacitors of 2 μF, 4 μF and 8 μF are connected in parallel. Their
equivalent capacitance will be
[c ]
8/7
μF (B) 7/8 μF (C) 14 μF (D) None of these
29.
The coupling between two magnetically coupled coils is said to be ideal if the
coefficient of coupling K
is
[d ]
Zero
(B) 0.1 (C) 2 (D) 1
30.Two
coupled coils with L1=L2=0.6 H have a coupling coefficient of k=0.8.The turn
ratio N1/N2will be
[ d]
4
(B) 2 (C) 0.5 (D) 1
31.
The product of the number of turns and flux linking with the coil is known as flux
linkage
32. An ideal voltage source & ideal current
source are connected in parallel. This circuit has [ a]
(a)Nortons
equivalent but not thevenins equivalent
(b)
Thevenins equivalent but not nortons equivalent
(c)
Both the thevenins equivalent and nortons equivalent
(d)
Neither thevenins nor nortons equivalent
33. If there are B branches and N nodes then the
number of equation will be [ d]
a)n-1
(b) b (c) b-n (d) b-n-1
34. Which of the following theorem is applicable
for both linear and non linear circuits [d ]
(a)
Superposition (b) thevenin’s (c) norton’s theorem (d) none of these
35. The unit of MMF is [ a]
(a)AT
(b) weber/ampere (c) henry (d) AT/M
36.
Maximum power transfer theorem can be applied to both ac and dc circuits
37.
When the superposition theorem is applied to any circuit, the depend voltage
source in that circuit is always active
38.
The superposition theorem requires as many circuits to be solved as there are sources
39.
While determining Rth in thevenin’s and norton’s equivalent all independent
sources are made dead
UNIT-3: Alternating quantities
SECTION-I: MULTIPLE
CHOICE QUESTIONS
1. An
alternating current is given by i=200 Sin(314t+π/3)amps. The maximum value
& frequency of the current are __________ [
a ]
(a) 200A, 50Hz (b)
100√2A, 50Hz (c) 200A,100Hz (d) 200A,25Hz
2. The length
of a phasor in a phasor diagram normally represents the __ values of the
alternating quantity. [ a ]
(a) Effective (b)
Average (c) Peak (d) None
3. The
standard supply frequency in India is ____________ Hz. [ b ]
(a) 25 (b) 50 (c)
60 (d) 100
4. Form Factor is the ratio of
[ c ]
A) RMS Value/Peak
Value B) Mean value/Peak value
C) RMS value/Mean
Value D)Mean Value/RMS Value
5. A60Hz power line voltage of 120V is applied across a
resistance of 10 ohms. The RMS value of current [ D ]
A) 168A B) 8.48A C)
16.8A D) 12A
6. OHM is the
unit of following except [B ]
A) Resistance B)
Capacitance C) Capacitive reactance D) Inductive reactance
7. In purely
inductive circuit [ C]
A) Reactive power
is zero B) apparent power is zero C) actual power is zero D) none
8. Which of
the following waves has the highest value of form factor [
A ]
A) Triangular wave B) sine wave C) square wave D) rectangular wave
9. RMS & Mean
value is the same in case of ____________ wave. [c]
(a) Sine (b) Half wave rectifier (c) Square (d) Triangular
10. In AC circuits, ISinφ is called __________
[
b ]
(a) Wattless (b) Reactive (c) Quadrature (d) Any of these
11. The phase difference between the
two waveforms can be compared only when they have same _________ [a ]
a)Frequency (b)
Peak Value (c) RMS Value (d) Average Value
12. The form factor of DC voltage is……………... [ c]
A.Zero B. Infinity C. unity D. 0
13. In a pure
capacitor, the voltage ……………… [c]
A. Is in phase with
current B. Is out of phase with current
C. lags behind
current by 90 deg D. leads behind current by 90 deg
14. A power factor
of zero indicates ………….. [B ]
A. purely resistive
element B. purely reactive element
C. combination of
both A & B D. none
15. What is the
phase angle of a series RLC circuit at Resonance? [ B]
A.
Infinity
B. Zero C. 45 deg D. 90 deg
16. What is the
phase angle of a series RLC circuit at Resonance? [ B]
A. Infinity B. Zero
C. 45 deg D. 90 deg
17. What is the phase angle of a series RLC circuit at Resonance? [ B]
A. Infinity B. Zero
C. 45 deg D. 90 deg
18. What is the total reactance of a series RLC circuit at Resonance? ….. [
A]
A. Zero B. equal to XL C. equal to XC D.
equal to R
19. The average value of an Unsymmetrical
alternating quantity is calculated over the ______ [ a]
(a) Whole cycle (b)
Unsymmetrical part of the waveform (c) Half cycle (d) None
20. The time period of an alternating quantity is
the time taken in seconds to complete one [ b]
(a)
Alternation (b) Cycle (c) half alternation (d) None
21. The algebraic sign of an IR drop primarily
depends upon the [ a]
(a)
Direction of flow of current (b) battery connections
(c)
Magnitude of current flowing through it (d) Value of Resistance
22. The power factor of an AC circuit lies
between ____ & ____ [ a]
(a)
0,1 (b) -1,1 (c) 0,-1 (d) none
23. A current is said to be alternating when it
changes in [ c]
A)
Magnitude only B) direction only C) both magnitude and direction D) none of the
above
24. The form factor is the ratio of [a ]
A)
Average value to rms value B) rms value to average value
C)
peak value to average value D) Value to rms value
25. In a series resonant circuit with the
increase in the value of Capaciter [ d]
A)
Resonant frequency will increase B) Q will decrease
C) Band width will
increase D) Both (A) and (B)
26. The power factor of a pure resistive circuit
is [a ]
a) 1 b) 0.2 lagging
c) 0.6 leading d) 0.8 lagging
27. The direction of current in ac circuit [ c]
(A)is
from positive to negative. (B) is always in one direction.
(C) varies from
instant to instant ( D) cannot be determined.
28. If the supply frequency of a pure capacitive
circuit is tripled , the current will be
[a ]
(A)Tripled (B)
one-third (C) nine times (D) one ninth
29 The power factor
of practical inductor is [ d]
(A)Leading (B)
unity (C) zero (D) lagging
30.
Electrical power converted into heat due to flow of an alternating current
through an ohmic resistance is called the [b ]
(A) Heating power
(B)True Power (C)Reactive Power (D)Apparent Power
31. In a purely inductive circuit _________ power
is Zero. [d ]
(A) Apparent (B)
Reactive (C) Inductive (D) True
32. In an R-L series circuit the power factor is
[b ]
(A) Leading (B)
lagging (C) Zero (D) Unity
33. The highest speed of a 50 Hz AC generator can
be [ b]
A) 6000 rpm B) 3000
rpm C) 1500 rpm D) 7000 rpm
34. Which of the following wave does not
represent an alternating quantity [d ]
A) Cosine wave B)
Triangular wave C) Rectangular wave D) None of these
35. A current is said to be alternating when it
changes in [ C]
A) Magnitude only
B) direction only C) both magnitude and direction D) none of the above
36. In a series resonant circuit with the
increase in the value of Capaciter [D ]
A)
Resonant frequency will increase B) Q will decrease
C) Band width will
increase D) Both (A) and (B)
37. The frequency of a DC supply is _____ HZ [D ]
(A)F
Hz (B) 16 ⅔ Hz (C) 50 Hz (D) Zero
38. The form factor of a sinusoidal wave form is
_____ [ C]
(A)
1 (B) 1.414 (C) 1.1 (D) 1.25
SECTION-II:
FILL IN THE BLANKS
1. The capacitive reactance of a circuit
decreases
with the
increase if frequency.
2. A Sinusoidal
voltage varies from Zero to maximum of 250V. The voltage at the instant of 60o
of the full cycle will be 216.5V
3. The power
consumed in an AC circuit will be minimum when the phase difference between
current & applied voltage is 90.
4. The symbol ‘j’
represents counter clock wise rotation of the
phasor 90˚ degrees.
5. An
alternating current is represented as i=70.7Sin (520t+π/6). The frequency &
RMS value of the current are 82.7 Hz, 50 A.
6. In R-L circuit current
lags the Voltage.
7. Current
magnification occurs in RLC
parallel circuits
8. The time period
of a sinusoidal with 200Hz frequency will be 0.005Sec
9. If the supply frequency of a purely inductive circuit is
doubled, the circuit current will be halved
10. The capacitance of 10 micro farad, will give the same
reactance as an inductor of 1H at 50 Cycles/Sec
11. Power factor of an Inductive circuit can be improved by connecting a
capacitor to it in series
12. The length of a phasor in a phasor diagram normally represents the rms values of the
alternating quantity.
13. The phasor combination of true power and useless power is apparent
14.Ratio of Voltage across inductor to applied voltage at
resonance is defined as Q factor
15. In series circuit …CURRENT………….. Acts as a
reference
16..In parallel circuit, ……voltage………………. acts as a
reference
17. Ratio of RMS value to the Average value is called as ……formfactor…………
18. Phasor diagram is used to represent the relation between two (or) more
Sine waves of same ____frequency______
19. Unit of susceptance is …… ………Siemens……….
20. The magnitude & phase of current vector is depend on the values of…………R, L,
C, F…………
21.
The opposition to the flow of alternating current is called as impedance
22.
Power factor of an ac circuit is defined as
R/Z
23.
A constant current of 2.8A exists in a resistor then the rms value of current
in resistor is 2.8A
24.
The length of a phasor in a phasor diagram normally represents RMS value of the alternating quantity
25.
The form factor of a sinusoidal wave is 1.11
26.
In a series R-L-C circuit, magnitude of resonance frequency can be changed by
changing the value of R,L
& C
27.
A sine wave has a frequency of 50 Hz. Its angular frequency is 100π radians
per second.
28.
The standard supply frequency in India is 50Hz
29.
The form factor is the
ratio of rms
value to average value
30.
The form factor for DC supply voltage is always unity
31.
Resonant frequency ‘fr ’ of a series R-L-C circuit is related to half power
frequencies f1 and f2 as fr=
32.
In an R-L-C parallel circuit, the power factor at resonance is unity
33.
Q-factor of a resonant circuit id defined as 2πX(Maximum Stored Energy/Energy dissipated per
cycle)
34.
The relation between Real power (P), Reactive Power (Q) and Apparent Power(S)
is ________
35.
Power factor of an AC circuit is defined as active power / apparent power
37.
Two voltage vectors are in quadrature and have effective values of 6 V and 8 V,
The sum of the two vectors is 10V
38.
The form factor of sinusoidal / cosine wave is 1.1
39.
An AC generator having 6 poles is required to generate voltage at 120 cps, The
speed of the generator is 2400rpm
40.
37. A four pole DC generator is running at 1500 rpm. The frequency of current
in the armature is 50HZ
41.
The current through the inductor is LAGGING with respect to the
applied voltage with respect to the applied voltage
42.
The AC supply is
completely described with magnitude & FREQUENCY
43. The
impedance of a pair of capacitors 3.18 μF connected to a supply of frequency 50
Hz is 1KΩ
44.
The units for apparent power ‘S’ is KVA or VA
45.
The RMS value of
sinusoidal voltage is 0.707V
46.
The phase angle between voltage and current in a pure inductance is 90˚
47.
In a RL series circuit the
magnitude of impedance is given by Z= 
ohms
UNIT-4: TRNSFORMERS
SECTION-1:
MULTIPLE CHOICE QUESTIONS
1. A Transformer will have low efficiency at
________________Load [C ]
A) Full load B) Half load C) No-load D) none
2. A transformer has an efficiency of 80% and works
at 100V, 4KW. If the secondary voltage is 240V, find primary current [a ]
(a)40A (b)30A (c)20A (d)10A
3.The no load current of a transformer is generally
of the order of _______the full load current [a ]
(a)less than 5% (b)more than 5% (c)equal to that
(d)zero
4. The open-circuit test on a transformer is
always made on [ a]
(a) low-voltage winding (b) high-voltage winding
(c) Either low or high voltage winding (d) none of
the above
5. The Principle of operation of a Transformer is
[ B]
(A) Electromagnetic Induction (B)Mutual Induction
(C) Varying a conductor in a magnetic field (D)
Electrostatic induction
6. The flux involved in the emf equation
of a transformer has [ D]
(A) RMS value (B) Average value (C) Total value (D)
Max. value
7. In a single phase transformer, with
subscripts 1 and 2 for primary and secondary windings[a ]
(A) E1N2= E2N1 and I1N1= I2N2 (B) E1N1=
E2N2 and I1N1= I2N2
(C) E1N2= E2N1 and I1N2= I2N1 (D) E1N1=
E2N2 and I1N2= I2N1s
8.Eddy current losses in a transformer core can be
reduced by _____ [ a ]
(a) Reducing the thickness (b) decreasing air gap in
the magnetic circuit
(c) Increasing air gap in the magnetic circuit. (d)
Increasing the thickness
SECTION 2: fill in the blanks
1.The
iron core in a transformer provides a LOW RELUCTANCE
path
to the main flux.
2. The type of
value of flux involved in the emf equation for a transformer is
MAXIMUM
3. The
transformation ratio of a transformer is N1/
N2
4. The primary
ampere turns of transformer is
EQUAL to secondary ampere turns.
5. The phasor
postion of magnetizing current component of an ideal transformer in phasor
diagram lags the applied voltage by 900
6. If
rated Dc voltage is applied instead of AC to the primary of a transformer then primary winding of the transformer will burn.
7.
If Pi be the iron losses and Pc be the copper losses on full load, then the
condition for obtaining the maximum efficiency at 3/4th full load is
Pc= (16/9) Pi
8.A
transformer can have Zero regulation at leading power
factor.
9.
The chemical used in breather is silica gel
10.
the no load current in a transformer lags the applied voltage by 75˚
11.
In a Transformer Core is laminated to reduce Eddy current loss
12.
Condition for maximum efficiency of Transformer is Constant
losses = variable losses
13. THE
efficiency of transformer is
(OR) 
14. The shot
circuit test is conducted to determine is COPPER LOSSES AND SERIES PARAMETERS
15. The core losses in a transformer consists of Hysteresis and Eddy current losses
16. The voltage regulation of a transformer can be
determined by conducting Open
Circuit (OC)
and Short Circuit (SC) tests.
17. The open-circuit test on a transformer
gives Iron losses
18. A transformer has full-load copper loss of 400
W. The copper loss at half-full load will be 100W
19. Transformer operates on AC only.
20 A transformer steps up the voltage by a factor
100. The ratio of current in the primary to that in secondary is 100
21. Efficiency of a transformer is maximum if Iron losses=cu losses
22. The Regulation of a Transformer is zero,
when the Power factor is leading
