DGCA Module 3 Important one line Question Bank | Electrical Fundamental

Question Bank | Important notes related to DGCA Module 3

1. Battery vent cap provides escape of gas & prevent escape of electrolyte
2. Trickle charge is required for trickle charge
3. Electrolyte used in ni cad battery is kOH & in lead acid battery H2SO4
4. In transformer core losses indicates or known as EDDY CURRENT & HYSTERSIS losses.
5. If transformer ratio is 100% , the transformer is called IDEAL TRANSFORMER
6. If V is volt , I is current , R is resistance , the Ohms law states V=IR
7. In an atom , if outer orbit has more than 4 electrons , it is INSULATOR
8. In a generator the shape of brush is RECTANGULAR
9. In a generator , when coil & magnetic lines are parallel , the voltage induced is ZERO
10. The unit of capacitance is FARAD
11. Basic formula of current is ,I =Q/T
12. The material Bismuth is in category of DIMAGNETIC material.
13. The unit of Attenuation is DECIBLES
14. The property of a material to oppose the magnetic flux is known as RELUCTANCE
15. Thermistor is NEGATIVE TEMP co efficient and if temperature increases , the resistance of thermistor DECREASES
16. The unit of inductance is called HENRY
17. In purely inductor circuit CURRENT LAGS VOLTAGE BY 90′
18. Di electrics are made up of INSULATOR
19. The unit of conductance is SEIMENS
20. The potentiometer has THREE terminals and Rheostate has TWO terminal .
    Q.21. In purely capacitive circuit, relation between voltage & current is LEADS
21. Transformers are rated in VA/KVA
22. In AC, relation between value & peak value is , RMSValue =PEAK/1.414
23. In Pis no. of poles & N is speed ,in an alternator , frequency F= PN/120
24. If cells/ batteries are connected in parallel AMPERE HOURS is additive & when connected in series VOLTAGE is additive
25. In generator , to obtain a uniform direction current COMMUTATOR is used .
26. In an ideal transformer ,the relation between input voltage & output voltage is EQUAL
    
27. In a transformer Eddy current losses & Hystersis losses are also known as CORE LOSSES
    
28. Where applied voltage and current are out of phase by 90 degree, they are said to bE QUADRATURE
29. In a three phase alternator , three voltages are 120′ electrical degree apart.
30. If in a circuit , current lags the voltage by 90 degree , the circuit is INDUCTIVE load.
31. The frequency of alternator depends on SPEED AND NUMBER OF POLES
32. In AC the resultant value is called RMS
33. In a simple generator , the no. of lines of force per unit area is known as FEILD STRENGTH
34. The value of AC, current & voltage is indicated by SINE WAVE
35. The working principle of transformer iS MUTUAL INDUCTION
36. In an atom , proton has POSITIVE charge.
37. The SI unit of magnetic flux is WEBER
    
38. The property of magnetism & magnetic flux depends on PERMEMABILITY
39. In generator ,Interpoles are always connected IN SERIES WITH ARMATURE WINDING
40. If P is resistivity ,L is length , A is area in circular mil , then formula for Resistance R = PL/A
41. Speed of motor depends on FREQUENCY,I/P POWER AND NUMBER OF POLES
42. In generator ,when speed & load are changing , then field distortion is counteracted by INTERPOLES
43. In motor , when armature rotates in a magnetic field , the induced voltage is called BACK EMF
44. Ohms Law relates , the current is DIRECTLY PROPORTIONAL TO VOLTAGE
45. When capacitors are connected in parallel, value of capacitance is INCREASES
46. In resistor fourth band of color band iS MULTIPLIER FOR % TOLERANCE
47. Application of photovoltaic cell is found on SATELLITE, SPACE PROPS, HAND HELD CALCULATORS AND WRIST WATCHES
48. In parallel circuits CURRENT remains same & in series VOLTAGE remains same
49. Magneto Motive force is FORCE
50. In an atom ,the particle which has smallest weight is ELECTRON
51. In a stable atom , which particle has neutral charge NEUTRAL
    
52. When secondary coil of transformer is nOt connected to any load , then the primary coil will draw SMALL MAGNETISING/LESS CURRENT current .
53. The induced current & magnetic field opposes the motion , is called LENZ’S law.
54. If cutting is 1 ampere, & resistance is 1 ohms, the power is 1 WATT
55. Which value of heat dissipation in AC circuit is equivalent to DC RMS VALUE
56. The filter used when it is required a particular range of frequency to be signed out or filtered from a wider range of frequency , the filter is BAND PASS
57. Magnets always exits in PAIRS
58. In transformers , the magnetic losses are also called HYSTERSIS AND EDDY CURRENT
59. In generators lap winding is used for HIGH CURRENT &LOW VOLTAGE & wave winding is used FOR HIGH VOLTAGE &LOW CURRENT
60. The relation between capacitance Resonance & frequency is X c= 1/2πFC
    62 Two resistances R1&R2 each of 8 ohms in parallel ,current I is 2 amps ,the power will be 16 WATT (Rt = R1R2/R1+R2)= 4 ohms P= ISquare,R , 2square 4 = ..16 Watt .
61. The unit of magnetic flux is WEBER of flux density is TESLA & of magnetic field strength is Oersted AMPERE/METRE
62. No. of electrons in inner most orbit is TWO
63. Resistance is inversely proportional to CROSS SECTIONAL AREA & directly proportionally to LENGTH
64. One Watt = 1 JOULE/SECOND Joules
65. While charging capacitor graph was plotted which shows CURRENT & VOLTAGE BOTH ( in term of v & I )
66. No. of complete charge & discharge cycle ,a battery can perform before its capacity falls below 80 percent , is called BATTERY LIFE CYCLE
67. Static charge that builds up during normal flight is dissipitated on .STATIC DISCHARGE WICKS
68. If resistance circuit is in parallel , the voltage will be SAME
69. For communication & radio system BAND PASS FILTER filter is used.
70. When capacitors are connected in DC , it shows SHORT Circuited.
71. When large amount of current is controlled & circuit has high power rating , the type of resistor used is WIRE WOUNDS
72. Two resistances R1&R2 ,connected in parallel, total resistance Rt= R1R2/ R1+R2
73. If a capacitor of 150 micro farad is connected to 3 volt , the charge Q =CE = 150.3= 450micro coulomb
74. The thermocouple effect is also known as SEABACK EFFECT & is used for TEMPERATURE SENSING& EXHAUST GAS TEMP INDICATOR
75. The unit for quantity of Electricity is COULOMB
76. The force that causes electrons to flow throuhgh a conductor , is called ELECTROMOTIVE FORCE
77. The opposition of a material to magnetic flux is called RELUCTANCE
    
78. The unit of reluctance is REL.
79. In synchronous motor , speed depends on FREQUENCY
80. Carbon is NEGATIVE temperature coefficient .
81. When a metal losses ion , it becomes +VE
82. Unit of resistivity is OHM.METER
83. In a alternator having 20 poles & speed is 300 rpm ,the frequency will be 50HZ
84. One KWH is equal to 3600( joules)
85. A 24 volt battery provides 5 coulomb charge for 2 second , then resistance of conductor is 9.6 OHM
86. EMF produced depends on rate of change of FLUX
87. If a work done is 1 joule in 1 second , then power is 1 WATT
88. Internal resistance of a battery when it is in discharge condition is MAXIMUM
89. When current flow is minimum or zero , magnetic line of force are in PARALLEL ( series or parallel )
90. If thermistor is positive temperature coefficient , if temperature increases the resistance INCREASES
91. When an atom gains electrons it becomes NEGATIVELY CHARGED
92. Metallic shielding is BAIDED COPPER WIRE
93. A battery whose reaction can be reversed is SECONDARY & whose reaction can not be reversed is PRIMARY
94. Material magnetized in lightly in opposite direction to the applied magnetic field , it is DIMAGNETIC MATERIAL
95. What is additive in parallel connection (choice – Resistance , Impedance , Capacitance ) CAPACITANCE
96. If I is current , R is resistance , Power loss in a circuit is , P=I2R
97. Current & Voltage are in phase in RESISTIVE circuit & phase angle is said to be 0
    
98. Synchronous speed of induction motor depends on F,P & N
    
99. Molecule is the smallest part of substance , which is called COMPOUND
100. Two resistors each of 2 ohms connected in series, if 2 amp current flow then power developed in circuit will be 16 WATT
101. In shaded pole motor starting torque is LOW & Power Factor is LOW( high or low )
102. Maximum no. of electrons in outer most orbit of an atom is 8
103. No. of electrons in outer shell of semiconductor is 4
104. If three capacitors ,each of 1 micro farad ,connected in series ,the net capacitance is 1/3 uF
105. In a capacitor the time required to charge to 63 percent of value of source is known as TIME CONSTANT
106. In DC motor, the electrical characteristics are TORQUE & aRMATURE CURRENT
107. In a multiple capacitor , if parallel plates are n , the number of capacitors are n-1
108. What is used to measure the flow of charge AMPERE( voltage,current, colour )
109. If 100 joules are consumed in 100 seconds, the power is 1 WATT
110. Rehostate is used to vary CURRENT & potentiometer is used to vary VOLTAGE
111. Rehostate & potentiometer are VARIABLE resistors ( fixed or variable )
     
112. In colour coding from left to right ,first band is red & second band is green , then number is 25
113. If cells are connected in series , then current is SAME across all cells & voltage is DIFFERENT at all cells ( in term of same / different )
114. In DC generators , the losses result from friction between brush & commutator is MECHANICAL loss
115. Dislodging an electrons from an atom will cause the atom to become POSITIVE charged.
116. An atom that has gained an extra no. of electrons is charged& and is called NEGATIVE ion.
117. In an atom NEUTRON has same mass as proton
118. Hunting in electric motors occurs due to VARYING LOAD & CHANGE IN FREQUENCY
119. Generators are rated in KW alternators in KVA
120. The purpose of fourth winding in three phase AC generator is FOR VOLTAGE DISTRIBUTION PHASE WISE
121. The generator output to commutator is DC ( ACor DC )
122. In LCR circuit, if if capacitance is increased by 4 times , impedance will INCREASES ( increase or decrease )
123. If OCV & CCV are known, the Internal Resistance = (OCV-CCV)/APPLIED VOLTAGE
124. In lead acid battery cell having multi plates has more negative plates than positive because Positive plates are prone to wrapping if chemical reaction is only one side , so negative plates is more, at side negative plate will be there
125. Internal resistance of aVlaclanche cell is about ohms 0.02 OHM
126. A capacitor rating is MAXIMUM VOLTAGE IT CAN TAKE WITHOUT RUPTURE( in term of voltage or
     current )
127. The different parts of aircraft are maintained at same potential , method is known as BONDING
128. When resistances are connected in parallel, the current is SAME( same or different in resistances )
129. If there happen to be short circuit between supply & earth ,it leads to CURRENT DRAWN WILL BE HIGH AND IT WILL BE DANGEROUS
130. In a three phase power system , A phase colour coding is RED colour .
131. If a material has low permittivity , it is DIELECTRIC( paramagnetic, dielectric , ferromagnetic ,diamagnetic )
132. The power is zero , the circuit will be purely RESISITIVE ( resistive, capacitive , inductive )
133. When transformer is at no load , current in secondary will be zero, in primary there will be IRON LOSSES loss ( core loss, iron loss , both, no loss )
134. The strength of electrostatic field between two charged bodies is directly proportional to STRENGTH OF CHARGE & inversely proportional to SQUARE OF DISTANCE BETWEEN THEM
     
135. The ability of a material to become magnitized is called PERMEABILTY
136. In dry cell graphite is mixed with Mno2, its purpose is TO REDUCE INTERNAL RESISTANCE
     
137. The capacity of no cad battery is is a function of TOTAL PLATE AREA IN CELL
138. To form a battery from cells , these are inter connected by STRAP
139. Ni- cad,Ni – zn, C zn , zn mn , which are primary & which are secondary battery FIRST TWO SECONDARY AND LAST TWO PRIMARY
140. If M is mass & V is velocity, Kinetic Energy = 1/2MV2
141. Disadvantages of shaded pole motor are LOW STARTING TORQUE & LOW POWER FACTOR
142. What exist between them if one charge is positive & another of different polarity PD/ EMF
143. Carbon resistor has first two band as yellow & blue, first two number will be 46
144. A narrow hystersis substance is best to make PERMANENT MAGNET( armature parts, transformer core, permanent magnets )
145. What causes flow of electrons POTENTIAL DIFF/ EMF( resistance, power, potential difference, current,)
146. Property of a coil to induce emf in near by coil is called MUTUAL INDUCTANCE
147. In an alternator if P is pole, N is speed, the frequency F= NP/120
148. Dielectrics are made up of INSULATORS
     
149. Generator can have BOTH( revolving field, rotating armature, both )
150. Magnetic potential is VECTOR quantity.( scalar or vector , none ,both )
151. In respect of average value & rms value , Form Factor = AVG VALUE/RMS VALUE
152. The losses due to bearing and friction in motor is called MECHANICAL loss.
153. Total resistance in a parallel circuit is equal to RECIPROCOL OF THE SUM OF THE RECIPROCOL OF THE INDIVIDUAL RESISYTANCEC
154. As per Kirchoffs law , algebraic sum of current entering a point is equal to the sum of current leaving that point , the circuit is PARALLEL ( series, parallel, both )
155. If inductors are connected in series, the total inductance is SUM OF INDIVIDUAL INDUCTORS
156. Inductive reactance is measured in OHM and like RESISTANCE
157. If capacitors are in parallel , total capacitance is SUM OF INDIVIDUAL CAPACITORS
158. When it is required to have a large capacitance with smaller size capacitor, type of capacitor used is ELECTROLYTE CAPACITOR

GIVE MOCK TEST ON MODULE 3

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