BEE first mid with explanations

               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, R_AB= R_BC =R_CA = 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   V_L=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 f_r=

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