Basic Electricity(panda Sir)

BASIC ELECTRICITY ELECTRICAL,BATTERY,GENERATORS & MOTORS 1. If Z is impedance, r is internal resistance and R is external resistance, then (a) Z= R + r (b) Z2 = R2 + r2 (c) Z= R2 + r 2 (d) None 2. Resistance for a straight conductor does not depends upon (a) length (b) shape of cross section (c) temperature (d) material 3. In a capacitor (a) capacity depends on separation of plates and measured in farads (b) capacity depends on area of plates and measured in farads (c) capacity depends on nature of dielectric material (d) all (3-57) 4. Identify the symbol (a) capacitor (b) condenser (c) resistor (d) both A&B 5. Amount of electron that can be stored on capacitor is proportional to (Capacitance of a capacitor) (a) both plate area and distance between them (b) plate area and does not depend upon distance between them (c) plate area and inversely proportional to distance (3-57) (d) distance between plates and inversely proportional to area 6. Working voltage of capacitor should be (a) At least 20% higher than applied (b) at least 50% higher than applied (c) equal to applied voltage (d) less than 50% than applied voltage 7. When capacitive reactance becomes equal to inductive reactance of a circuit it is called (a) phase-in (b) phase-out (c) resonant (3-67) (d) impedance matching 9. Ohm’s law is

(a) (d) 11. called (a)

I ohm V (b) V ohm I (c) I ohm R V ohm R The opposition offered in AC circuit are impedence (b)

resistance

12. Relation between volt, ampere and Weber is given by a. amp/volt square –Weber b. amp X volt – Weber c. volt/amp – Weber d. None 13. Which of the following issued as voltage regulator device (a) carbon pile voltage regulator (b) magnetic amplifier regulator (c) transistor regulator (d) all are correct 14. When two sphere of same mass, one is +ve charged and other is –ve charged, then new mass will (a) change (b) unchanged 15. If the conductor is of 4 ohm and it stretched to twice of its length then its resistance is (a) 1 ohm (b)8 ohm (c) 12 Ohm (d) 16 Ohm 16. A and B are big and small battery having same emf. Internal resistance of battery A is (a) Less than B(b) Greater than B (c) equal to B (d) Unaffected 17. Which statement is correct (a) force is exerted on charged particle (b) force is applied on charged particle moving along with magnetic field. 18. Electrical power and energy is expressed in terms of (a) Kilo-watt and kilo watt hour respectively (285) (b) Watt and joule respectively (c) Watt and watt hour respectively (d) Watt and Newton 20. A wire is connected to constant voltage supply while the length and radius is doubled – (a) electric field is half (b) electric field is double (c) heat is unchanged (d) electric field remain same 21. Heat energy is converted to electrical energy in

(a) Transducer (b) Thermocouple (c) Both 22. In straight conductor the resistance do not depend upon (a) temperature (b) length (c) material (d) shape of cross section 23. Electrical bounding and shielding is used to (a) avoid accumulation of static charge (b) give stability in radio reception (c) both (a) & (b)(271) (d) None 24. The work done on a moving charge from one point to another is depend upon (a) the path taken (b) position of two points 26. Which offers uniform magnetic field (a) earth (b) bar magnet (c) circular magnet (d) horse shoe magnet 27. If 28 volt current is passed through resistant of 10 ohm the power consumed by the component is (P=V Square/R) (a) 78.4 watt (b) 780 Watt (c) 784 Watt (d) 78 Watt 28. Refer the figure : what will the ohmmeter read (a) 20 ohm (b) 0 ohm (c) 40 ohm 29. If the rpm of the driver gear is 60 then the rpm of driven gear is (a) 120 rpm (b) 100 rpm (c) 60 rpm (d) 30 rpm 30. The resistance of conductor depends on (a) temperature (b) length and material (c) cross sectional area (d) all 31. In an inductive circuit (a) current lags behind voltage by 90 deg. (b) current leads behind voltage by 90 deg. (c) cross sectional area (d) None 32. (a) (c)

Which one is unpaired battery – accumulator (b) diode – NRV AC generator – vortex generator (d) EMF – MMF

33.

Which one is not primary cell

(a)

Zn-carbon (c)

34.

Kirchoff’s law is applicable in

(a)

dc (b) ac dc ckt having resistance both a & c

(c) 35. (a)

(b) Lead acid cell Alkaline cell

(d)

Magnetic flux depends upon no of turns (b) rpm rate of cutting flux (d) all

36. Power factor in d.c. circuit is (a) unity (b) infinite zero (d) none 37. (a) (c) 38. (a)

Unit of electrical energy is Kilowatt hour ampear watt hour all Power can be calculated by V2/R (b) l 2/R V.I (d) all

(c)

(c)

(b) (d)

(C)

39. Effect on the part by varying frequency in eddy current testing (a) skin effect (b) 40. Batteries are connect in series (a) total current is equal to the sum of the individual current (b) total voltage is equal to the sum of the individual voltage (c) both a & b (d) None 41. When three individual resistance are connected in parallel to each other which of the following is correct (a) R=R1+R2+R3 (b) I/R = I/R1 + 1/R2 + I/R3 42. (a) (c)

Unit of magnetic flux is weber (b) both a & c

Newton meter (d) none

43. (a) (b) (c) flux

A magnetic force always exert on a charged particle a uncharged particle charged particle parallel to magnetic

44. Essential parameters for calculating power are (a) force (b) distance traveled (c) time doing work (d) all of the above 45. 1 HP is usual to (a) 735 electric watts electrical watts (c) both a & b

(b)

746

(d)

none

46. Ohm’s law does not hold for (a) diode (b) NPN transistor (c) Hg (d) &b

(i) (ii) (iii) (iv) 53.

Bonding of Fuel tank done to :-

(a)

Discharge static electricity

54. When dia and length of wire doubled, heat should be (a) (b) (c)

47. When coil of wire is placed horizontal to the earth surface and a bar magnet dropped form the top (a) fall with acceleration equal to ‘g’ (b) fall with acceleration less than ‘g’ 48. A micro switch will open or close a circuit with the movement of (a) 1/16 or less (b) 1/16 or more (c) both (d) None 49. An ac circuit consists of inductance of 10 ohm , capacitance 1 ohm and resistance 8 ohm the impedance of the circuit is ………………….. (a) 6 ohm (b) 10 Ohm (c) 5.5 ohm (d) 8 ohm 50. An ac circuit has inductance 3 ohm and resistance of 4 ohm then impedance of the circuit is (a) 3 ohm (b) 4 ohm (c) 5 ohm (d) 7 ohm 51. Insulation resistance measurement, ground, continuity and short circuit testing can be done by:

doubled unchanged (9A-272) None of above

55. Resistance of straight conductor does not depend upon (a)

both a

Shunt type ohmmeter Megger Multimeter All are correct ( 3-91)

Material Shape of conductor (9A-272) (c) Temp (d) length

(b)

56. Induced voltage in coil of conductor depend upon :(a) (b) (c) (d)

No of turns Field strength Speed of rotation all are correct (4-2)

57. Mark the correct statement regarding transistor :(a) E, B are forward biased and B, C are reverse biased. 58. The value of di-electric constant ‘k’ of Mica is(i) (ii) (iii) (iv)

3.0 6.0 (3-58) 6.5 4.2

60. To protect vibrating contact from burning, capacitor is connected (i) or in series

either across the contact points

(ii) (iii) (iv)

across the contact points in series with contact points None

61.

Test for insulators (i) Di-electric strength test (ii) Insulation resistance test (iii) Di-electric resistance test and brake down voltage test (iv) Di-electric strength test and insulation resistance test 62.

A/C electrical bus bars are made of : (i) (ii) (iii) (iv)

63.

Aluminum Copper Aluminum and copper (3-15) None

Which one is near to transducer:

(i) Tochelle salt (ii) (iii) (iv) 64.

65.

Generator and attenuator and probc Motor and amplifier Capacitor and zener diode Battery

Frequency of A.C (Source): (i) 55 (ii) 60 (iii) 56 (iv) 57 Max. (i) (ii) (iii) (iv)

Frequency (in figure) of reed: 55 112 56 110

66. How much power must a 24-volt generator furnish to a system which contains the following loads; Unit Rating One Motor (80% efficient) 160 Watt Three position lights 20 Watt each One heating element 5 amps One anti collision light 3 Amps (i) (ii)

402 Watts 385 Watts

(iii) (iv)

450 Watts 472 Watts

67. A 12 V electric motor has 1000 watts input and 1H.P. output, maintaining the same efficiency, how much input power will a 24V, 1H.P. electricl motor require (Note 1 H.P. = 740w) (i) 1000W (ii) 2000W (iii) 500W (iv) As in (ii) and less current will flow 68. How much power is being furnished to the circuit (i) 1150 w (ii) 5750 w (iii) 5290 w (iv) 2300 w 69. A 24 V source is required to furnish 48W to a parallel circuit consisting of four resistors of equal value , what is the voltage drop across each resistor: (i) 12 V (ii) 3V (iii) 24V (iv) 48 V 70. If resistor R, is disconnected at the junction of R4 and R5 as shown , what will the ohmmeter read ? (i) 2.76 Ohm (ii) 3 Ohm (iii) 12 Ohm (iv) 6 Ohm 71. When calculating power in a reactive or inductive ac circuit , the true power is (i) More than the apparent power (ii) Less than the apparent power in a reactive circuit and more than the apparent power in an induction circuit (iii) More than the apparent power in a reactive circuit and less than the apparent power in an inductive circuit. iv) Less than the apparent power.(3-64) 72.

The equivalent resistance is (a) (b) (c) (d)

2 4 1 3

Ω Ω Ω Ω

73. The ammeter can be converted in to voltmeter by connecting

(a) coil (3-89) (b) coil © coil (d)

a resistor in series with meter a resistor in parallel with meter a capacitor in series with meter

2.76 Ω

(ii)

12 Ω

(iv)

75. To ensure the proper demagnetization of a part take near to the compass, the deflection of compass needle more that (i) 30 degree minutes require demagnetization again (ii) 1 degree no demagnetization (iii) 1 degree require component to be demagnetized again and test to be repeated (iv) 1 degree minute to require component to be demagnetized 76. In a circuit the capacitor and inductor are in parallel then (i) Low voltage drop (ii) No current will pass through the ckt at resonant frequency (iii) Current will flow in the ckt 77. In a circuit the power is 28 watt and voltage is 28 volt then the resistence is (i) (iii) 78.

28 Ohm 1 Ohm

(ii)

(i)

reducing edy current loss (9A-

(ii) (iii)

Low reductance 1+2

361)

None

74. If resistor R is disconnected at the junction of R4 and R5 as shown, what will the ohmmeter read ? (i) 3Ω (iii) 6Ω

79. In transformer thin laminated core is used for

80. If the coil length is decreased in the circuit, the power (i) Remains same Increases (iii) Decreases Zero

(ii) (iv)

81. The ordinary efficiency of transformer is maximum when (i) It runs at half full load (i) It runs at full load (iii) It’s cu-loss equals iron loss???(iv) It runs slightly overload 82. The resultant resistance between P & Q as per the figure shown is (i) 2 Ohm (ii) 3 ohm (iv) 18 Ohm

(iii) 6 ohm

83. Which statement is correct for both series & a parallel dc cct (i) Powers are additive (ii) Voltages are additive (iii) Currents are additive (iv) Elements have individual currents 84. A magnitude of emf applied across the primary

56 Ohm

Power factor is

(i) Effective power Kw/apparent power KVA (3-64) (ii) Cosine of phase angle+1 (iii) Sine of phase angle +1 (iv) Only (i) is correct

(i) primary (iii) secondary (iv) secondary 85.

The number of turns in the The number of turns in the The resistance of primary &

Kichoff’s voltage law is concerned with

(i) IR Drops Battery EMF (III) Junction voltage Both (i) & (ii) (9A-289) 86.

(ii) (iv)

A fuse is used in electrical circuit to (i)

indicate the consumption of

power (ii) Break the circuit when power is off (iii) Maintain constant current (iv) Break the circuit in case of over current 87. In an A.C. ckt the ratio of KW/KVA represents (i) Load (iii) (iv)

Power factor factor Form factor Diversity factor

(ii)

88. On small dia a/c electrical cables only the recommend stripping tools should be used for removing the insulation. On no account should a (i) (ii) (iii) (iv)

Site cutting plier to be used Knife be used Heat be used Any of the above

89. The opposition offered by a coil to the flow of alternating current is called (disregard resistance) (i) (ii) (iii) (iv) 90.

Impedance Reluctance Inductive Reactance(3-53) Inductance and frequency

In ac circuit the effective voltage is

(i) Less than the predetermined voltage (ii) Equal to the maximum instantaneous voltage (iii) Greater than the maximum instantaneous voltage (iv) Less than the maximum instantaneous voltage

91. Unless otherwise specified, any values given for current or voltage in an ac circuit are assumed to be (i) Instantaneous values (ii) Mean values (iii) Effective values (3-47) (iv) Maximum values 92. The potential difference between two conductors which are insulated from each other is measured in (i) (ii) (iii) (iv)

Volts Amperes Farads Coulombs

93. The correct way to connect a test voltmeter in a circuit is (i) (ii) (iii) the load. (iv)

Equal to the voltage of unit In series with a unit Between the source voltage and In parallel with a unit

94. If three resistors of 3 ohms, 5 ohms and 22 ohms are connected in series in a 28-volt circuit, how much current will flow through the 3-ohm resistor? (i) (ii) (iii) (iv)

0.39 amperes 9.3 amperes 1.05 amperes 0.93 amperes

95. Which of these will cause the resistance of a conductor to decrease? (i) Decreases the length or the cross-sectional area. (ii) Decrease the length or increase the cross-sectional area. (iii) Increase the length or decrease the cross-sectional area. (iv) Decrease the length and the cross section area. 96. The voltage drop in a conductor of known resistance is dependent of (i)

The voltage of the circuit.

(ii) Current of the circuit. (iii) Only the resistance of the conductor and does not change with a change in either voltage or amperage. (iv) The amperage of the circuit.

(ii) Potentiometer is 2 terminal and use high voltage (iii) Rehostat is 2 terminal and use low voltage (iv) Potentiometer is 3 terminal and use low voltage

98. When calculating power in a reactive or inductive ac-circuit, the true power is

103. The magnitude of induced emf produced in a coil when a magnet is inserted in it does not depend upon

(i) More than the apparent power. (ii) Less than the apparent power in a reactive circuit and more than The apparent power in an inductive circuit. (iii) Less than the apparent power.(365) (iv) Any of the above.

(a) no of turns in coil (b) resistance of coil (c) magnetic moment of magnet (d) Speed of rotation of magnet (magnetic strength)

99. Transfer of electrical energy from one conductor to another without the aid of electrical connections (i) (ii) (iii) (iv) head and as

Is called induction. Is called radiation. Is called air gap transfer. Will cause excessive arcing and a result is impractical.

104.

(a) amplifies the low input signal to high output signal (b) used as a rectifier (c) used in transducer set (d) both (a) & (c) are correct 105.

EMF is produced in generator by

(a)

Lenz’s law (b) Electromagnetic induction Right hand fleming rule (d)

(c) 100. When referring to an electrical circuit diagram , what point is considered to be at zero voltage (i) The circuit breaker (ii0 atmosphere reference (iii) The switch The ground reference

The (iv)

101. If an electrode is removed from the cell and to know its potential difference it is compared with (i) (ii) (iii)

110. the

(i) Rehostat is 3 terminal and use low voltage

High discharge tester is used to check

111. A cathode (electron emitter) used in thermionic emission must have following characteristics

An electrode in another cell Area of plates Number of separator

MTCS

None

(a) voltage of battery in normal operating condition (b) efficiency of condenser (c) penerator output (d) voltage of battery to find its charge condition and if recharging is required

(c) 102.

A transformer

(a) high matching point (b) high matching strength low work function draw extension lines

(d)

112. In a transformer is primary frequency changes from 50Hz, keep the pick voltage constant then frenquency

(a) (b) (c) (d)

increases in secondary by ratio 60/50 decreases in secondary by ratio 50/60 both 1 and 2 none

113. Mark the correct statement for transformer (a) mutual induction is working principle (b) output voltage depends on transformation ratio/turn ratio (c) all of the above 114. Precision wire wound resistors are wounded with (a) carbon (b) copper (c) magnanin(278) above

(d) all of the

115.

Transformer used for :-

(a)

Transfer power at same frequency (b) Transistor circuit (c) a and b are correct

Ohmmeter (9A-364) Voltmeter and ammeter Ammeter All of the above

117. Parts of the Airframe must be demagnetized (i) So they will not affect retraction of under carriage (ii) So they will not affect instruments (iii) Otherwise the components may fail to operate (iv) De magnetic sign is required only for engine parts not air frame 118.

Current transformer is opened upon (i) Step up (iii) Uni transition

(i) (iii)

Same Doubled

(ii)

Half???

120. A magnitude of the emf of transformer does not depend upon (i) The magnitude of emf applied across the primary (ii) The number of turns in the primary (iii) The number of turns in the secondary (iv) The resistance of primary & secondary 121. The all day efficiency of transformer depends primarily on

116. Which one among following is used to find out that whether concerned transformer is step up or stepdown: (i) (ii) (iii) (iv)

119. If voltage of step up transformer is doubled and transformer ratio is 1:2 then the output through the coil is

(ii) Step down (iv) None

(i)

It’s copper loss (ii) The amount of load (iii) The duration of load (iv) Both (2) & (3)

122. In ammeter (D’Arsonavol type), two oppositely wound spring are used, for the purpose of: (i) Compensating expansion and contraction of springs, because of temperature changes (9A- 322) (ii) Removing backlash (iii) as (i) and having stand by (iv) All of the above 123. How do you connect an Ammeter in a circuit. (a)

across the Battery (b) across the generator (c) in series with the load (3-89)

124. How do you convert the Galvanometers into voltmeter :(a)

connect high R in series (3-89) low R in series (c) low R in parallel (d) high R in parallel

(b)

125. Galvanometer is transferred in ammeter

(iv) As in (ii) and may be expressed as the numbers of mill volts across the meter when full scale current flows through it

(a) By connecting low resistance in series to the galvanometer (b) By connecting high resistance in series to the galvanometer (c) By connecting low resistance in parallel to increase range (d) By connecting high resistance in parallel to increase range 126.

Shunt ohmmeter measures

(a)

low resistance(3-91) (b) high resistance precision resistance (d) infinite resistance

(c)

135.

(i) (ii) (iii) (iv)

Range of ammeter can be increased by

(a) (b) (c) (324) (d)

connecting high resistance is parallel connecting high resistance in series. connecting low resistance in parallel

(a)

series both a & b

107.

Shunt motor is used in

(a)

L/G and flap operation Hydraulic motor Gyro meter Both a & b

(c)

(e)

Current measuring device (3-88) Voltage measuring device Resistance measuring device Both (i) and (iii)

106. For constant voltage, …………` generator used is

128.

129. in

D’Arsonval meter movement is a

(b) (d)

shunt none

(c)

(b) (d)

108. AC induction motor is used in place of the DC motor because

connecting low resistance in series The sensitivity of voltmeter is measured (a) Ohm/ volt(3-90) (b) (c) Farads (d) ampere … Volt/meter (f) Volt/ohm

Watt

131. If acid is spilled over skin from an a/c battery then it cleaned with (a) water (b) water & boric acid (c) water & bicarbonate of soda (d) all 134. The sensitivity of a meter movement is usually expressed as (i) The amount of current required to give full scale deflection (ii) The amount of current required to give half scale deflection (iii) As in (i) and may be expressed as the numbers of mill volts across the meter when full scale current flows through it (324)

(a) (b) (c) (d) commutator

of less weight it requires less maintenance it is less expensive than dc motor it does not use brush and

109. A generator relay has silver and copper lining (a) to provide greater bearing surface and low resistance (b) copper made contact and break contact and increase life (c) for the purpose of spark (d) to prevent arcing 136. In the shunt motor the field winding is connected in parallel or in shunt with the armature winding (i) Field winding is connected directly across the power supply(4-34) (ii) Produces low starting torque but high speed at light loads (iii) Relative speed between the field and rotor

137. If load is removed from shunt motor and is in open circuit then the current is (i) Maximum (ii) Minimum (iii) Depend upon the apparent power 138.

field is rotating Armature is rotating Armature is stationary

144. (a) (b) (c) (d)

Speed of the motor can be increased by field winding X-sectional area of the field (armature) Exitation winding All

A series wound d.c. motor will produce

(i) Low starting torque (ii) High starting torque (iii) 1+ its speed depends upon the value of load (iv) 2+its speed depend the value of load(4-34) 140. The wastage of energy in a potentiometer can be minimized by keeping (i) The resistance as low as possible (ii) The resistance as high as possible (iii) The resistance potentiometer lower than that of load (iv) None 141. In a differential relay system the charging of battery happens, when 22V generated voltage is there, through (i)

3 field windings & 2 armature one permanent magnet 3 field windings & 2 armature two permanent magnet 2 field windings & 3 armature one permanent magnet One field windings & 1 armature one permanent magnet

In single phase induction motor (i) (ii) (iii)

139.

(i) windings & (ii) windings & (iii) windings & (iv) windings &

Voltage relay coil (ii) Differential relay coil (iii) Main contactor (iv) Both 1 & 2

142. In an aircraft alternator the reverse current cut out relay can be avoided due to the presence of (i)

Rectifier unit (ii) Voltage regulator (iii) Current limiter (iv) None

143.

In a brush less alternator there can be

145. Speed of motor increase when load current decrease because of (a) frictional loss between motor’s moving parts (b) frictional loss between field winding and other parts (c) induced back emf decreases(449) (d) None 146. (a)

Generator frequency depends on No of poles (b) RPM (c) both a & b (d) None

147.

A series wound d.c motor will produce: (i) Low starting forque (ii) High starting forque (iii) (i) + it’s speed depends upon the value of load (iv) (ii) + it’s speed depend the value of load(4-34) 148. In a single phase inductive motor the field produced is (i) Rotating field (ii) Pulsating & rotating field (iii) Pulsating stationary field(4-37) (iv) Stationary but not pulsating field 149. The counter emf is induced in the d.c. motor (i) Armature(4-31) (ii) Field (iii) Both 1 & 2 (iv) None 150. Which of the following method can be employed for reversing the direction of rotation of d.c. motor

(i) Changing the polarity of supply to field & armature (ii) Using split field windings(4-32) (iii) Using double-pole, double throw switch (iv) Both 2 & 3

(ii) To As in (i) and they keep the neutral plane parallel distorted field (iii) As in (i) and they keep the neural plane perpendicular to distorted field (iv) As in (ii) and improve the efficiency output and service oife of brushes

151. A permanent magnet rotary inverter consists of (i) A d.c. generator & a.c. generator (ii) A d.c. motor & a.c. motor (iii) A d.c. motor & a.c. generator(435) A d.c. generator & a.c. motor

156. Which statement is true regarding differential switch (i) It connects the generator to main bus when generator voltage exceeds the bus voltage by 0.25 to 0.45 v (ii) It connects the generator to main bus when generator voltage exceeds the bus voltage by 0.35 to 0.65 V. (iii) As in (i) and it disconnects the generator when nominal reverse current flows from bus to generator (iv) As in (ii) and It disconnects the generator when nominal reverse current flows from bus to generator

152. A thermal switch as used in an electric motor is designed to (i) Slow down the speed of motor. (ii) Close the integral fan circuit to allow cooling of the motor. (iii) Open the circuit in order to allow cooling of the motor. (iv) Reroute the circuit to ground. 153.

In a series wound DC generator

(i) The field coils are composed of a few turns of large wire(4-33) (ii) The field coils are composed of more turns of thin wire (iii) As in (i) and when the load is increased, the voltage decreases (iv) As in (ii) and when the load is increased, the voltage increases 154.

157.

In shunt motor

(i) The field winding is connected in parallel with armature winding (ii) The resistance in field winding is high and current through the field winding is constant (iii) The torque will vary only with the current through armature (iv) All the above are correct 159.

An under compounded generator has

To exite a self excited DC generator (i)

A DC generator is used initially to

(ii) (iii)

It exite him self with out source A DC motor is used

exite (i) No-load voltage value less than full load voltage (ii) Full load voltage less than the no load voltage (iii) As in (i) and changes in terminal voltage with increasing load depends upon the degree of compounding (iv) As in (ii) and changes in terminal voltage with increasing load depends upon the degree of compounding(4-10) 155.

160. How many terminals can be taken out from stud (a) one terminal per stud (b) two terminal per stud (c) both a/c and van are kept at equal potential with a wire any no of terminals can be taken out from one stud

In a DC generator interpoles are used 161. (i)

To reduce field distortion

Diamagnetic material has permeability

(i) greater than one AND NON FERROUS METALS ARE CALLED PARAMAGNETIC (ii) less than one 9A-302 (iii) very much greater than one (iv) equal to one

BATTERIES 1. The electrolyte of a NI-cad battery is the lowest when the battery is (i) (ii) (iii) (iv)

In a charged condition Being charged In a discharged condition (314) Under load condition

2. How can the state of charge of a nickel cad battery be determined (i) By measuring the specific gravity of the electrolyte (ii) By measured discharged (iii) By the level of the electrolyte (iv) None of the above 3. When a charging current is applied to a nickel-cadmium battery, the cells emits gas only (i) cycle.(314) (ii) cycle. (iii) (iv)

Toward the end of the charging In the beginning of the charging When the electrolyte level is low. If they are defective.

7. Aircraft batteries should be disconnected as a precaution against fire (i) When soldering is carried out adjacent to wiring looms or cables (ii) When welding is carried out on A/C structure (iii) When ground run is given with a external battery (iv) When A/C is parked in side the hanger 8. Lead battery capacity …………………… out after initial charge and thereafter a… (i) One month 3 months (iii) 6 months (iv) year at the time of C of A renewal

5.

Storage of Ni-Cd battery

(i) Battery fully charged and electrolyte drained (ii) As in 1 clean the terminals (iii) Battery discharged and full with electrolyte (iv) Maintain cored water level also 6. (i)

The active material of Ni-cd battery are

Nickel hydroxide (ii) Powdered cadmium and its hydroxide (iii) 30% solution of caustic potash (iv) All of the above.(314)

Every

9. Acid of lead acid battery neutralized with :(a) Boric Acid carbonate of soda(3-39) (c) None of above 10.

4. The +ve plate in discharged Ni-cd battery is of (i) Nickel hydroxide (ii) Nickel oxy hydroxide (iii) cd-hydroxide (iv) cd-oxyhydroxide

(ii)

(b)

Bi-

A/C battery is :

(i) An auxiliary source of electrical energy (ii) The main source of electrical energy in large A/C (iii) (i) + the color of positive plate in the lead acid battery is chocklet brown (9A306) (iv) (ii) + (iii) 11. In a lead-acid battery the separators have vertical ribs on the side facing the + ve plate. It’s purpose is (i) To provide electrical conductivity between + ve & -ve plate through the electrolyte (ii) To provide a path for plate material sediment to settle to the bottom of the cell (9A-308) (iii) To prevent electrical short have +ve & -ve plate (iv) All are correct

12. The material & color of positive plate in the lead-acid battery is – (i) (ii) (iii) (iv)

PbO, Gray PbO, chocklet brown PbO2, chocklet brown PbO, Gray

13. A temperature correction in sp Gravity of electrolyte is not necessary at the following temp(i) 65 F (ii) between 70 degree F & 90 Degree F (9A-272) (iii) between 90 degree – 100 degree F (iv) All are correct 14. In AC batteries are charged by the following method(i) Constant Voltage method (9A313) (ii) Constant Voltage variable current method (iii) Constant current method (iv) Any of the above 15. White powder on a properly serviced Ni Cd battery indicates(i) (ii) (iii) (iv)

Normal operation Over charging (9A-314) lader charging Overfilled electrolyte

16.

What determines the amount of current which will flow through a Battery while it is being charged by a constant voltage source ? (i) battery. (ii) battery. (iii) battery. (iv)

The total plate area of the The state-of-charge of the

(i) Prevent sediment build up from contacting the plates and causing A short circuit.(3-35) (ii) ……………. of the electrolyte in order to proved from cooling of the plates (iii) Ensures that the electrolyte quantity ratio to the number of plates and plate area is adequate (iv) 1 & 3 are correct. 18. The lead acid cell is said to be charged completely when (i) The cells starts gasing freely (9A313) (ii) 3 consecutive reading of hydrometer is same (iii) Voltage per cell becomes 2.2V & above (iv) All the above 19. (a) (c)

Negative plate of Ni-Cd battery is of pure cadmium (b) nickel hydroxide cadmium hydroxide (d) none

20. Which statement is correct (a) battery terminal voltage is equal to battery emf. (b) Batter terminal voltage is less than batter emf (c) batter terminal voltage is more that batter emf. (d) depends on direction of current flow. 21.

In nickle cadmium battery

(a) during discharging the current flows from the negative pole to positive plate and oxygen atoms are driven out from the positive plate (b) electrical leakage is measured by millimeter between cell and casting (c) both a & b

The ampere-hour capacity of the None of the above.

17. The purpose of providing a space underneath the plates in a lead acid battery’s cell container is to

22. In lead acid battery temperature correction factor is necessary (a) for temperature above/below 80 deg F ( .4 every 10 deg plus or minus) (b) for temperature above/below 100 deg F (c) for temperature above/below 120 deg F

(d)

no correction is made

23. When a new Ni-cd battery is installed its cell seal is opened and pour electrolyte to ensure the full charge battery (a) no charge is required (b) charge is given and boost up and (A) (b) as in (b) and suddenly installed in a/c service (d) as in (b) and after two hours check the electrolyte and installed in service 24. What type of batter charger is recommended for final charging of Ni-cd battery (a) (b) (c) (d)

constant current charger constant voltage charger both a & b any one of the above

25.

Ni-cad battery is rapidly charged with

26. For a battery to have high ampere hour capacity and high terminals voltage (a) (b) (c) (d)

should have low internal resistance should have high internal resistance does not depend on internal resistance None

27.

Electrolyte used in lead acid battery

(a)

KOH Dilute H2SO4 Concentrated H2SO4 None

29.

(i) (ii) (iii) (iv)

Cell balancing Recycle Check Voltage recovery None

31. To neutralize acid deposits in lead acid battery compartments and to treat acid burns from chemical cleaners use: (i) boric powder (ii) mild soap solution (iii) Baking soda (9A-308) Oil soluble detergent cleaner 32. Function of antimony in a grid of leadacid battery is

(a) constant current and variable voltage (b) constant voltage and variable current(3-40) (c) variable voltage and variable current (d) both a & b

(c)

30. An A/C battery fails to perform 80% of its rated capacity which one should be carried out

(a) (b) material (C) susceptible (d)

(a) (b) © (d)

1.275 to 1.300 at 80 deg F. 1.23 to 1.25 1.2 to 1.25 1.2 to 1.275

34. Negative plate of lead-acid battery is made of (a) lead (3-35) lead oxide © lead peroxide none

(d)

(a) during all times in lead acid battery servicing (b) in Ni-cd battery at the end of charging (c) when battery is overcharged (d) both a & c

harden the lead and make it less to chemical action all the above

33. The sp. Gravity of electrolyte in a fully lead acid charged battery must be between

(b)

Hydrogen gas is emits in the battery

to make possible finer casting providing space for more active

35.

KOH from eyes is washed with (i) Water (ii) Boric acid Mild soapy water

(b) (d)

(iii)

36. Where battery or there acids have been spilled, the affected parts should then be brushed with a

(i) Diluted Acetic acid for nickel cd batteries to neutralize electrolytic (ii) Dilute solution of sodium bicarbonate for lead acid batteries (iii) Dilute solution of borax and nitric acid for both lead acid and nickel cad. batteries respectively (iv) (i) and (ii) are correct (3-39/42) 37. Due to sparking in confined place in the presence of water, what is produced

(a)

38.

(ii) (iv)

The active material of NI-cd battery are (i) Nickle hydroxide (ii) Powdered cadmium and its hydroxide (iii) 30% Solution of caustic potash (iv) All of the above(3-41)

39. The electrolyte used in the NI-CD battery is (i) a 30% solution (by weight) of KOH in distilled water (3-41) (ii) A 40% solution (by weight ) of KOH in distilled water (iii) A 50% solution (by weight) of koh in distilled water (iv) None 40. ….Battery will not freeze until extremely low temperatures are reached because (i) The acid in the plates, thereby increasing the specific gravity of the solution. (ii) Most of the acid is in the solution. (iii) Increased internal resistance generates sufficient heat to prevent freezing. (iv) Decreased internal resistance does not generating heat to prevent freezing. 41. To neutralize the surface of Ni-cad battery compartment

water (c)

42. Cellophane is used to protect the NiCad battery from a) Shorting between plates Thermal runaway c) Avoid leakage of electrolyte these 43.

(i) Corrosion Errosion (iii) Nitric acid Sulphuric acid

boric acid???check (b) baking soda (d) all

b) d) All of

Vicious cycle is connected to (a) Nickel cadmium battery (b) Sulphuric acid battery (c) Dry cell (d) None of the above

44. When applying gen left hand rule, your index finger points in the direction the lines of magnetic flux travel, your thumb indicates the conductors direction of movement, and your second fingure indicates the direcion of induced EMF. 45. When using the motor right hand rule, your right index finger indicates the direction the magnectic flux flows, while your second fingure indicates the direction of current flow and your thumb the direction the coil rotates. 46. Series wound DC generator have poor vol regulation capabilities and are therefore not suitable for ac. However they are suitable for situations where a const RPM and const load are applied to the gen. 47. The output and vol regulation capability of shunt type DC generator make them suitable for light to medium duty use on ac. However, most of these units have generally been replaced by DC alternators. 48. The amount of vol produced by a compound wound DC generator depends on the degree of compounding. The flatcompound generator is one in which the no load and full load vol have the same value. The under compoud gen has full load vol is less than the no load vol and an over compound gen has a full load vol that is higher than the no load vol.

a) Ampere b) Volt d) Coulomb

c) Watt

ELECTRICITY(QB) 1. The amount of electricity a capacitor can store is directly proportional to a) Distance between the plate and inversely proportional to the plate area b) Plate area and is not affected by the distance between the plate. c) Plate area and inversely proportional to the distance between the plate d) None of these 2. The correct way to connect a test volt meter in a circuit is a. In series with a unit b. Between the source voltage and the load c. In parallel with unit d. Both (a) and (c) are correct 3.

Typical application of Zener diode is as a. Full wave rectifiers b. Half wave rectifier c. Voltage regulator d. Amplifier 4. The method used to rapidly charge a Nickel Cadmium battery utilizes a. Constant current and constant voltage b. constant current and varying voltage c. Constant voltage and varying current d. Varying voltage and varying current 5. Potential difference between two conductors insulated from each other is measured in a) Ampere b) Coulomb c) Ohm d) Volt 7. Which term means .001 ampere a) Micro ampere b) Milli ampere c) Kilo ampere d) Nano ampere 8.

Unit used to express electrical power is

9. Transfer of electrical energy from one conductor to another without the aid of electrical connection is a) Induction b) Air gap transfer c) Not possible d) Possible but will cause excessive arcing thus not practical 10. Magnetic lines of force pass most readily through a) Aluminium b) Copper c) Irond) Titanium 11. In a straight conductor, the resistance is not affected by a) Length b) Temperature c) Shape of cross section d) Material 12. Power and work are measured in a) Watt and force b) Watt and joule c) Ampere hour and joule d) Farad and joule 14. The change in resistance depends upon a) Temperature b) Material and length c) Cross sectional area d) Both b) and c) are correct 15. Most extensively used material in aircraft electrical cables is a) Rubber and silk b) Nylon and cotton c) Teflon d) Both b) & c) are correct 16. In a parallel circuit a) Total resistance is less than smallest resistor b) Total resistance decreases when one of the resistance is removed c) Total voltage drop is same as total resistance d) All are correct 17. If there are ‘n’ numbers of cells, each having a voltage of ‘E’ and resistance ‘R’, then voltmeter connected across the electrolyte will indicate

a) nE b) (n-1)E None of these

c) n(n - ½)E

d)

18. A 12V bulb is connected in series and draws 3 amperes current from a 12V battery. Its resistance and power will be a) 36 ohms, 4 W b) 4 ohms, 36 W c) 1 ohm, 12 W d) None of these 19. i) AC current passing through a conductor creates emf around the conductor ii) Frequency of radio wave radiated equals the frequency of the applied current a) Only i) is correct b) Only ii) is correct c) Both i) and ii) are correct d) Neither i) nor ii) is correct 20. Flux used for commutator wires and electrical connections a) Zinc chloride b) Zinc chloride by diluting with 50% alcohol c) Alcoholic solution of rosin d) Rosin 21. While installing battery (Ni-Cad) on a/c you must inspect a) Ventilation system of a/c b) Cable for chaffing c) Quick disconnection mechanism d) All of these 22. What will be value of resistance of yellow, red, orange and gold a) 42000  10% b) 42000  5% c) 12000  5% d) 22000  10% 23. One of the effect of negative feed back in amplifiers is to a) Increase the noise b) Increase the harmonic distortion c) Decrease the bandwidth d) Decrease the harmonic distortion 25. The device used to measure very high insulation resistance of electric cable is a) High resistance voltmeter b) Megger / Insulation resistance tester c) Iron vane meter d) Ammeter of high range

26. If six cells are connected in series of each E volts, the total voltage of the battery will be a) 6E b) 3E c) 4E d) 12E 27. Special test equipment comprising a meter and two cables each of specific length, is required for checking the resistance of bonding. A meter widely used , consists of an ohm-meter operating on a) Principle of current ratio b) Principle of voltage ratio c) None of these 28. Cellphane is used to protect the Ni-Cad battery from a) Shorting between plates b) Thermal runaway c) Avoid leakage of electrolyte d) All of these 29. Two quantities are said to be in phase with each other when a) The phase difference between two quantities is zero degrees b) Each of them pass through zero values at the same time and rise in the same direction c) Both a) & b) d) None of these 30. When calculating power in a reactive or inductive ac circuit, the true power is a) More than the apparent power b) Less than the apparent power c) As in b) in reactive circuit and as in a) in inductive circuit d) None of these 31. Diodes are used in electrical power circuit primarily as a) Switches b) Rectifiers c) Relays d) Contactors 32. If three resistors of 3, 5 and 22 ohms are connected in series in a 28V circuit, how much current will flow through the 3 ohms resistor? a) 9.3 amps b) 1.05 amps c) 0.93 amps d) 10.05 amps

33. What is the value of a resistance if given colour codes as brown, black, brown, black and brown. a) 1010 ohms b) 1000 ohms c) 101 ohms d) 10.1 K ohms 34. What is the value of a capacitor if given colour codes are orange, orange, blue and white. a) 33nF b) 33μF c) 33pF d) 3300μF 35. The output of a astable multi-vibrator is a) Triangular wave b) Saw tooth wave c) Sinusoidal wave d) Square wave 36. In an oscilloscope by varying intensity control, what actually varied internally? a) Cathode voltage b) Anode voltage c) Grid voltage d) Cathode current 37. The phase difference between voltage and current in a purely resistive circuit is given by (A) 00 (B) 900 0 (C) 45 (D) 1350

b) 12 amp c) 15 amp d) 1 amp 42. Which plating process provide excellent base for paint a) Cd – Plating b) Zn – Plating c) Granodizing d) All of the above 43. Which treatment give excellent base for paint a) CR – Plating b) Parkerizing c) Metal spraying d) Zn – plating 44. The process use zinc as a medium for plating a) Parkerizing b) Sheradizing c) Galvonizing d) Both b) and c) 45.

The term 10-5 farads mean a. 1 mili-farad b. 10 micro-

farad c. 10 nano-farad

38. One micro farad is equal to a) 0.001 milli farad b) 100 milli farad c) 1000 milli farad d) 10 milli farad 39. To smoothen the DC in rectifier, we employ a) LPF b. HPF c) BPF d) None

46. A capacitor consists of two a) conductors separated by an insulator called the di-electric. b) insulators separated by a conductor. c) insulators separated by air medium. d) conductors separated by air medium. 47. in

In a capacitor electric charge is stored (a) metal plates

40. The Voltage / Current across the short circuit a) V = max I=0 b) V=0 I = max c) V=0 I=0 d) V = max I = max 41. Two resistances of 15, 12 ohms each are connected in parallel across a supply, giving 27 ampere, then current through 15 ohm will be a) 27 amp

d. None

(c) both (a) & (b) 48.

49.

Unit of m.m.f. is (a) weber (c) maxwell

(b) di-electric (d) none of these (b) gilbert (d) henry

Joule/coloumb is the unit of (a) electric field potential ??? (b) potential (c) charge (d) none of these

50. In a lead-acid battery, excessive formation of lead sulphate occurs due to (a) idleness of battery for a long time (b) low level of electrolyte (c) persistent under charging (d) all of them 51. Common impurity in a battery electrolyte is (a) dust particle (b) iron (c) lead crystals (d) sodium chloride 52. Overcharging of lead-acid battery will cause (a) excessive gassing (b) loss of active material (c) increase in temperature resulting in buckling (d) all of them 53. The energy of a capacitor having capacitance ‘C’ and voltage ‘V’ is given by (a) 0.5 CV2 (b) CV (c) C2V

(d) 0.5 C2V

54.

One unit of magnetic flux is given by (a) Weber (b) Weber per meter square (c) Square root of Weber (d) Henery 55.

Generators works on the principle of (a) Faraday’s law of electromagnetic induction (b) Ohm’s law (c) Biot - severt’s law (d) Gauss’s law

60. The ability of magnet to restore magnetism is called (a) Retentivity (b) Permitivity (c) Store ability (d) both (a) & (c) 61. If ‘Im’ is the maximum current for sine AC then its R.M.S value is given by (a) 0.707 Im (b) Im (c) 0.5 Im (d) 1.414 Im 62. The relationship between voltage and current in a purely inductive circuit is given by (a) Voltage leads the current by 90° (b) Current lags the voltage by 90° (c) both (a) & (b) (d) None of the above 63. By voltage division rule the voltage drop V1 in the circuit will be (a) V1 = (R2 x Vs) / (R1+R2) (b) V1 = (R1 x Vs) / (R1+R2) (c) V1 = Vs x (R1+R2) / R1 (d) None 64 If inductance is doubled and the capacitance is halved , then resonant frequency F0 (a) Doubled (b) Halved (c) Remains same (d) Squared root of F0 65.

56. The Capacitance of a parallel plate is given by (a) Ac / d (b) A2C / d (c) Ad / c (d) None 57. If there are ‘N’ number of cells, each having voltage E and internal resistance ‘r’ are connected in series, then the resulting e.m.f of the circuit is given by (a) NE volt (c) E volt

(b) E/N volt (d) NEr volt

50000000 Hz stands for (a) 5 MHz (b) 0.5 MHz (c) 50MHz (d) 500 MHz

69. Which statement is correct? a) Battery terminal voltage is equal to battery emf. b) Battery terminal voltage is less than battery emf. c) Battery terminal voltage is more than battery emf. d) Depends on direction of current flow.

71. High discharge tester is used to check the a) voltage of battery in normal operating condition. b) efficiency of condenser. c) generator output. d) voltage of battery to find its charge condition and whether recharging is required. 72. Electrical power and energy is expressed in terms of (a) Kilo Watt and Kilo Watt Hour respectively (b) Watt and Joule respectively (c) Watt and Watt Per Hour respectively (d) Watt and Newton 73. Three phase winding rotate with 1800 rpm in magnetic field having 8 poles, its frequency will be (a) 120 Cycle/Sec (b) 800 Cycles/ Sec (c) 1200 Cycles/ Sec (d) 1800 Cycles/ Sec 74. Kirchoff’s Law is applicable to (a) DC (b) AC (c) DC circuit having resistance (d) AC & DC 75. Two wires each one meter long are kept at a distance of 0.02mt. apart. If 1 amp current is flowing through each wire, then force acting in the wire will be a) attractive if the direction of the current flowing through wires is same. b) attractive if the direction of the current will be opposite. c) repulsive if direction of the current will be reverse. d) Both (b) and (c) are correct. 76.

The symbol represents

(a) SCR, rheostat respectively (b) rheostat, thyristor respectively (c) resistor, FET (field effect transistor) respectively (d) none of the above

77. In which condition the bridge is said to be balance? (a) R1 is increased, R2 is decreased (b) R3 is increased, R4 is decreased (c) R2 is increased, R3 is decreased (d) when G is constant 78. In case of battery which of the following quantity can be stored? (a) energy (b) charge (c) current (d) none of the above 79.

In a dry cell battery (a) carbon electrode is placed centrally surrounded by aluminium chloride electrolyte. (b) zinc chloride is placed centrally surrounded by aluminium chloride electrolyte. (c) carbon electrode is placed centrally surrounded by zinc chloride electrolyte. (d) both (a) and (c) are correct. 80. The identical insulated wire coils are hung from air so that they are facing each other and supplied with same direction a.c. (a) both are attracted to each other (b) both are repelled (c) clockwise rotation (d) anticlockwise rotation 81. Rheostat varies (a) amount of current (b) amount of voltage (c) both (a) & (b) (d) none 82. Potentiometer varies (a) amount of current (b) amount of voltage (c) both (a) & (b) (d) none

83. At the center of a coil, amount of flux is concentrated maximum at (a) starting of a coil (b) end of a coil (c) center of a coil (d) remain equal at all places

84. Negative plate of lead acid battery is (a) lead (b) lead peroxide (c) lead sulphide (d) spongy lead 85. Plates of lead acid battery is made of (a)lead + antimony on which active material is attached. (b)lead + iron on which active material is attached. (c)antimony + iron on which active material is attached. (d) none 86. MMF. is measured in Gilbert and symbolized by the capital letter. (a) G (b) F (c) M (d) W 87. Solenoid relay is operated on (a) high current (b) low current (c) high voltage (d) low voltage 88. Construction of separator of a lead acid battery is made in such a way that it circulates the electrolyte freely around the plates in addition it also provides a path for sediments to settle. (a) at the side of cell (b) at the top of cell (c) at the bottom of cell (d) none 89. Thermal protector is used to (a) protect a motor (b) to open the circuit automatically (c) it operates when temperature is very high (d) all of the above 90. S/W designed for momentarily operation (a) micro s/w (b) push button s/w (c) toggle s/w (d) none 91. Rotary S/W are used in (a) voltmeter selector s/w s/w (c) both (a) & (b) 92.

(a) intermitenty (b) continuously (c) could cause over heating if operated continuously (d) both (a) and (c) 93. Oil capacitors generally restricted to be used in (a) radio transmitting equipment (b) radar transmitting equipment (c) both (d) none 94. In fixed mica capacitor the dielectric is made of (a) metal plate (b) mica (c) both (a) & (b) (d) none 95. Mica prevents as a dielectric (a) arching between the plates (b) can withstand higher voltage (c) both (a) & (b) (d) none of these 96. The capacitor which provides large capacitance in small physical size is (a) oil capacitor (b) mica capacitor (c) electrolytic capacitor (d) paper capacitor 97. Wet-electrolytic capacitors must be mounted on (a) horizontally (b) vertically (c) any position (d) none 98. The working voltage of a capacitor depends on (a) type of material used as a di-electric (b) thickness of di-electric (c) frequency (d) all of the above 100. Power factor is the ratio of a) True power / apparent power b) Apparent power / true power c) Zero power / true power d) None of the above

(b) ignition (d) none

Starter relay s/w is made to operate

101. Transformer works on the principle of a) Self induction b) Mutual induction c) Electromagnetic induction

d)

Magnetic induction

102. The factor, which determines whether a given transformer is stepped up or steeped down, is given by a) Current ratio b) Voltage ratio c) Power ratio d) Turns ratio 103. The purpose of iron core in transformer is a) Given electrical energy from the source b) Isolates primary with secondary c) Join primary with secondary d) Provides low reluctance for magnetic lines of force 104. If the ratio of the transformer input voltage to the output voltage is same as the turn ratio then, transformer is said to be a) 50% efficient b) 110% efficient c) 100% efficient d) 25% efficient 105. Which of the following transformer can approach 100% efficient a) Iron core transformer b) Ferrite core transformer c) Copper core transformer d) None of these

The resistance of the conductor comprising of the turns of the coil Due to no. of turns None of the above 110. The range of paper capacitor is given by a) 200 micro micro farads to several micro farads b) 400 micro farads to 20 micro farads c) 1 micro farad to 1000 micro farads d) 200 micro farads to 400 micro farads 111. In radio and radar transmitters we generally prefer to use (a) Oil capacitor (b)Paper capacitor (c)Mica capacitor (d)Electrolyte capacitor 112. The range of mica capacitor is (a)50 micro micro farads to 0.02 micro farads (b)10 micro farad to 40 micro farads (c)Greater than 40 micro farads (d)None of these 114. Clamper is used to a) Cut any portion of AC cycle b) Shift its DC level c) Change the frequency d) Adjust the AC level

106. The range of frequency in the case of audio transformer is a) 40 to 20000 c.p.s b) 20 to 20000 c.p.s (360) c) 100 to 10000 c.p.s d) 10 to 10000 c.p.s

115. In conductor a) Valence band is empty only b) Conduction band is full only c) Both are overlapped d) VB, CB never combined

107. RF transformer utilizes Iron core Copper core Magnetic core Air core (360)

116. Two resistors (R1, R2) of 30 and 20 ohms respectively, are connected in parallel across a 20V source. The current through R1 branch would be a) 12A (b) 10A

108. The symbol of autotransformer used for communication or navigation circuit is (there is no symbol for iron core)

117. Which letter show as process code for achromatise a) A b) B c) C d) D

109. Copper loss in a transformer is caused by Due to iron core

118. Symbol indicate a) Electrical s/w b) Chemical s/w c) Electrolytic s/w

d)

Electro-thermal s/w

119. a)

The vacuum tube has Directly heated anode Indirectly heated cathode Directly heated cathode d) Indirectly heated anode

c)

138. The symbol indicates b)

120. For aircraft generation plant inductor is 1H. The value of capacitor should be a) 1 / (800 π)2 farad b) (800 π) farads c) (400 π) farads d) √800 π farads 121. In one time constant, the capacitor charges to a) 36.8% of its maximum value b) 63.2% of its maximum value c) 98% of its maximum value d) None 1TC- 63.2 % 2TC- 86.5% 3TC- 95% 4TC- 98% 5TC- 100%

Conductor Capacitor Condenser Variable Condenser 139. If supply voltage = 30V, then working voltage of capacitor could be 90V 45V (50% more than supply vol) 50V 55V 140. If electrolyte from a lead acid battery is split in the battery compartment, which procedure should be followed (a) Apply boric acid solution to the affected area followed by the water rinse (b) Rinse the affected area thoroughly with the clean water. (c) Apply sodium-bi-carbonate solution to the affected area followed by the water rinse (d) All of the above

ELECTRICAL GENERATORS AND MOTORS 122. Two resistances of 15, 12 ohms each are connected in parallel across a supply, giving 27 ampere., then current through 15 ohm will be a) 27 amp b) 12 amp c) 15 amp d) 1 amp 136. Which is true statement about capacitor? a) c)

Blocks DC Blocks AC

b) d)

Allows DC None

GENERATOR 1. Generators works on the principle of a) Faraday’s law of electromagnetic induction(4-2) Ohm’s law Biot-severt’s law d) Gauss’s law 2. The Tension of brushes to provide brush pressure is approx. a) 6 Psi b) 8 Psi c) 10 Psi d) 12 Psi

137. In a series connection 3. (a)Voltage is same across each element (b)Current is same in each element (c)Both are correct (d)None

A four pole generator will have a) 2 interpole b) 4 interpole(4-11) c) 6 interpole d) 8 interpole

4. In a 3 phase system, the phase winding is spaced symmetrically so that the voltage induced is a) 90o apart b) 120o apart(4-21) c) 60o apart d) 180o apart 5. To avoid armature reaction of small DC generator (1000 watt or less) type. The method used is a) Interpole Method b) Brush setting method c) both (a) & (b)(4-11) d) None of these 6. Compensating winding is used in series with interpole winding to a) Increase the life of brushes b) Distortion of field c) Reduces radio interference d) All the above 7. Staggering slots are used in armature of a DC generator to a) Minimise ripple voltage b) Maintain constant output c) Minimise eddy Current loss d) None of these above 8. A 3 four pole alternator, running at 6000 rpm will have frequency of a) 100 c/s b) 200 c/s c) 300 c/s d) 400 c/s 9.

12. An engine driven 50 Hz alternator has a speed of 750 rpm. How many poles it has? a) 6 poles b) 4 poles c) 2 poles d) 8 poles 13. The frequency of emf generated by a generator depends upon its a) Speed b) No. of ploles c) Machine rating d) Both a) & b)(426) 14. Two quantities are said to be in phase with each other when (a)The phase difference between two quantities is zero degrees b) Each of them pass through zero values at the same time and rise in the same direction c) Both a) & b) d) None of these 15. The figure shown here is of A simple gear train and the gear ‘D’ moves at half speed of gear ‘A’ As in ‘a’ & the gear ‘D’ moves in the same direction of the gear ‘A’ A compound gear train & the gear ‘D’ moves in the opposite direction of the gear ‘A’ A simple gear train and the gear ‘D’ moves in the opposite direction at a double speed of gear ‘A’

AC generator works on the principle of

a) Faraday’s law of electro-magnetic induction b) Mutual induction c) Self induction d) All of these 10. The relationship between back emf and applied voltage in case of a dc motor is given by a) Eb = V + Ia Ra b) Eb = V – Ia Ra c) Eb = V d) None of these 11. The direction of rotation of dc motor can be determined by a) Fleming’s right hand rule b) Fleming’s left hand rule(4-3) c) Lenz’s law d) Ampere’s law

100T

30

30

A

B

C

50T D

16. To get a basic D.C. generator from A.C. generator which of the following arrangement is made? By replacing the slip rings of the A.C. generator with commutator(390) b) By the addition of extra slip rings c) By connecting a rectifier d) None of the above 17. The rotating part of a DC generator is called

a) Armature

Field coil b. Yoke (4-6) d. None of these

c.

18. Variations of D.C. voltage generated by D.C. generator is called a) Ripple(4-4) b. R.M.S. c. Average d. Crest 19. made a) b) c) d)

The brushes in generator are generally up of High grade carbon(4-4) High grade silicon High grade selenium High grade zinc

22. The e.m.f generated in armature’s conductor of a D.C. machine is of nature a) A.C b) D.C c) Both d) AC and DC 24. The “ripples” generated in DC generator may be reduced by using a) More loops or coils(4-4) b) loop or coils c) Both d) of the above

Less None

25. There must be an ______ number of poles in any generator a) Even(391) b) Odd c) Both d) None of the above 26. a) b) c) d)

The purpose of slotting in armature is To increase mechanical safety(392) To increase electrical safety To increase both safety None of these

32. The output voltage of a series wound D.C generator may be controlled by a) Using a rheostat in parallel with the field windings(394) b) Using a rheostat in series with the field windings c) Both a and b d) None of the above This kind of gen can be used where constant load and constant RPM are applied to gen. 33. If a constant voltage is desired, which one of the D.C generator we would prefer Series wound D.C generator Shunt wound D.C generator(4-9) Both a and b None of these 34. In a compound wound generator the magneto motive force is equal to the a) Sum of series and shunt field component(4-10) b) Multiplication of series and shunt field component c) Square of series and shunt field component d) Square root of series and shunt field component 35. A generator in which the no load and full load voltages have the same value is called (a) Flat compound generator(4-10) Shunt generator (B) Series generator Both b and c

28. In DC machine the commutator surface is highly polished to a) Reduce friction(393) b) Reduce eddy current loss c) Both d) None of these

36. Compound generators are usually designed to be Over compounded(4-10) Under compounded Flat compounded All of these

29. Which of the following DC generator(s) can never be used with airplane? a) Series wound D.C generator( because of poor regulation)(394) b) Shunt wound D.C generator c) Compound wound D.C generator d) All of the above

37. In a situation where voltage regulation is of prime importance we prefer to use a) Compound generator(4-10) b) Series generator c) Shunt generator d) All of these

38. a) b) c) d)

Differential generators are Constant current generator(4-10) Constant voltage generator Constant power generator None of these

39. The main application of differential generator is a) Electric arc welding(4-10) b) Fans c) Turbines d) All of these 40. If the shunt field of a compound generator is connected across both the armature and series field, then the connection is said to be a) Long shunt connection(4-10) b) Short shunt connection c) Parallel connection d) Both a and b 41. Three wire generators are designed to deliver 240 or 120 volts from either side of the neutral wire 120 volts or 360 volts 220 V or 440 V Both a and c

42. called a) b) c) d)

The distortion of the magnetic field is Armature reaction(4-10) Field reaction Both a and b None of these

43. For parallel operation, the generators normally preferred are a) Shunt generators b) Series generators c) Both a and b d) Compound generator 44. In D.C generators, a inter pole field coils are connected In series with armature winding In parallel with armature winding In series with load(4-12) In parallel with load 45. In D.C generators the brushes are always placed along a) Magnetic neutral axis b) Geometrical neutral axis c) Bisector of GNA and MNA d) There is no hard and fast rule for this