ELECTRICAL ENGINEERING [UKSSSC (JE) ELECTRICAL/ELECTRONICS]

Transcription

1 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: How uch energy is stored by a 00 H inductance when a current of A is following through it? a) J b) 0.5 J c) 5.0 J d) 0.05 J. For the circuit shown below, find the resistance between points P & Q. a) Ω b) Ω c) 3 Ω d) 4 Ω 3. The rate of change of current in a 4 H inductor in Aps/sec. Find the voltage across inductor. a) 6V b) 8V c) V d) 0.8V 4. Find the node voltage V A. a) closed path b) group of interconnected eleents c) open terinal of an eleents d) junction of two or ore eleents 9. The area of the hysteresis loop will be least for one of the following aterials. It is? a) wrought iron b) silicon steel c) hard steel d) soft iron 0. The agnitude of AT required establishing a given value of flux in the air gap will be uch greater than that required for Iron part of a agnetic circuit, because: a) air is a gas b) air is a good conductor of agnetic flux c) air has the lowest relative pereability d) iron has the lowest pereability. The unit of luinous flux is a) candela b) luen c) lux d) steradian. The voltage across the kω resistor of the network shown in the given figure is a) 6V b) 5.66V c) 6.66V d) 5V 5. In a pure inductive circuit if the supply frequency is reduced to /, the current will? a) be four ties as high b) be doubled c) be reduced by half d) be reduced to one fourth 6. When a source is delivering axiu power to the load, the efficiency will be? a) below 50% b) above 50% c) 50% d) axiu 7. The internal resistance of a voltage source is 0Ω and has 0 volts at its terinals. Find the axiu power that can be transferred to the load a) 5 W b) 5 W c) 0.5 W d).5 W 8. A node in a circuit is defined as a a) V b) 4 V c) V d) 6 V 3. For painful shock, what is the range of electric shock current at 50 Hz? a) 0 A b) 3 5 A c) 0 3 A d) 5 0 A 4. What is the power consued by the resistor of 0Ω connected across 00 V source? a) 300 W b) 00 W c) 500 W d) 50 W 5. The latching current of SC is 8 A. Its holding current will be a) 6 A b) 8 A c) 54 A d) A 6. Thevenin s theore cannot be applied to: a) passive circuit b) active circuit

2 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: c) nonlinear circuit d) linear circuit 7. There are 3 laps 40 W, 00 W and 60 W. To realise the full rated power of the laps they are to be connected in: a) Parallel only b) Series or parallel c) Series only d) Series-parallel 8. In a three-phase syste, the volt apere rating is given by? a) 3 V L I L b) V phi ph c) V LI L d) 3 V I L L 9. A linear circuit is one whose paraeters: a) None of the options b) change with change in current c) change with change in voltage d) do not change with voltage and current 0. The unit for pereability is: At a) H / b) At c) Wb d) Wb. The Superposition theore is used when the circuit contains: a) a single voltage source b) passive eleents only c) active eleents only d) a nuber of voltage sources. One sine wave has a period of s, another has a period of 5 s, and other has a period of 0 s. Which sine wave is changing at a faster rate? a) all are at the sae rate b) sine wave with period s c) sine wave with period of 0 sec d) sine wave with period 5 s 3. An active eleents in a circuit is one which: a) dissipates energy b) receives energy c) both receives and supplies d) supplies energy 4. If in an -L-C series circuit, the frequency is below the resonant frequency, then a) X C < X L b) X C > X L c) X C = X L d) None of the options 5. If the power factor is high, then the consuer axiu KVA deand: a) increases b) reains constant c) becoes Zero d) decreases 6. During the resistance welding, the heat produced at the joint is proportional to? a) Current b) Volt-Apere c) I d) Voltage 7. Which of the following PNPN device has a terinal for synchronizing purpose? a) SUS b) Diac c) Triac d) Schitt trigger 8. A priary cell has an ef of.5 V. When short circuited, it gives a current of 3 A. The internal resistance of cell is? a) 0.5 Ω b) 0. Ω c) Ω d) 4.5Ω 9. Electrical esistivity is : a) High for copper as well as for alloy b) Low for copper and high for alloy c) High for copper and low for alloy d) Low for copper as well as for alloy 30. In dc operation of fluorescent tube, the life of the tube a) eain sae b) Decreased by about 80% as that with ac operation c) May increase or decrease d) Increases by about 80% as that with ac operation 3. If the nuber of turns of a coil is increased, its inductance. a) none of the options b) increased c) decreased d) reains the sae 3. A resistor is connected across a 50 V source. The current in the resistor if the colour code is red, orange, orange, silver is?

3 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: a).4 A b) A c). A d) 4 A 33. Mutual inductance between two coils is 4 H. If current in one coil changes at the rate of A/sec, then ef induced in the other coil is? a) 8 V b) V c) 0.5 V d) 5.0 V 34. The e..f. induced in a coil of N turns is given by: (according to Lenz Law) d d a) N b) N dt dt dt d) N d d c) dt 35. The device which cannot be triggered by voltage of either polarity is a) Diac b) Traic c) Schotkey diode d) SUS 36. An electric heater draws 3.5 A fro a 0 V source. The resistance of the heating eleents is approxiately? a) 3Ω b) 3.Ω c) 385Ω d) 38.5Ω 37.The current I in the electric circuit shown below is? a) 3.7 A b) A c).7 A d).7 A 38. In a Parallel LC circuit if the lower cut-off frequency is 400 Hz and the upper cut off frequency is 800 Hz. What is the band width? a) 800 Hz b) 400 Hz c) 400 Hz d) 500 Hz 39. If 750 A is flowing through kω of resistance, what is the voltage drop across the resistor? a) 4.6 V b) 46 V c) 8.5 V d) 8.5 V 40. If two capacitance C and C are connected in parallel then the equivalent capacitance is given by C C a) C C b) C C c) C C d) C C 4. If the co-efficient of coupling between two coils is increased, utual inductance between the coils a) changes depends on current only b) is increased c) is decreased d) reains unchanged 4. When a series L circuit is connected to a voltage source V at t = 0, the current passing through the inductor L at t = 0 + is a) infinite b) L V c) zero d) V 43. In an -L series circuit, the phase difference between applied voltage and circuit current will increase if a) X L is increased b) is increased c) X L is decreased d) supply frequency is decreased 44. A series circuit has = 4Ω, X L = Ω and X C = 9Ω and is supplied with 00 V, 50 Hz Calculate the power. a) 6400 W b) 8000 W c) 4, 400 W d) 9,00 W 45. Two sinusoidal currents are given by the equations i 50sin( t ) and 4 i 5sin( t ). The phase difference 6 between the is degrees. a) 5 b) 30 c) 45 d) 75

4 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: The reactance of farad capacitance when connected to a DC circuit is a) infinite b) Ω c) 0.5Ω d) zero ohs 47. A supply voltage of 30 V, 50 Hz is fed to a residential building. Write down its equation for instantaneous value. a) 63 sin 34.6 t b) 30 sin 34.6 t c) 35 sin 34.6 t d) 36 sin 34.6 t 48. Magnetic lines of force coing fro a agnet a) intersect at infinity b) intersect within the agnet c) cannot intersect at all d) cancel at pole faces 49. The ain advantage of teporary agnets is that we can a) change the agnetic flux b) use any agnetic aterial c) decrease the hysteresis loss d) agnetize without any source 50. The agnetic aterial used in peranent agnets is a) iron b) soft steel c) nickel d) alnico 5. Hysteresis is the phenoenon in the agnetic circuit by which a) H lags behind B b) B lags behind H c) B and H are always sae d) setting up a constant flux is done 5. In an SC a) Gate current is directly proportional to forward break over voltage b) as Gate current is raised, forward breakover voltage reduces c) Gate current has to be kept on continuously for conduction d) Forward break over voltage is low in the forward blocking state 53. A circuit has inductance of H. If the circuit current changes at the rate of 0 A/sec, then selfinduced ef is a) 5 V b) 0. V c) 0 V d) 0 V 54. The B H curve for will be a straight line passing through the origin. a) air b) soft iron c) hardened steel d) silicon steel 55. A current of 5A flows in a resistance less choke fro a 00 V alternating source. The energy consued in the choke is a) 0 J b) 4.4 J c) 500 J d) 000 J 56. The Q-factor of a series resonant circuit is given by a) L C c) / LC b) d) LC C L 57. For the circuit shown in figure, the voltage across the capacitor during steady state condition is a) 0 V b) 4 V c) 6 V d) V 58. Find AB for the circuit shown in figure. a) 8 Ω b) 30 Ω c) 45 Ω d) 68Ω 59. Calculate the total susceptance of the circuit shown in figure.

5 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: when, V 0V ; when 0, I 4A; when, 5, the current I is a) 6.67 Ʊ b).87 Ʊ c) 0.6 Ʊ d) 0.08 Ʊ 60. A 00 W, 00 V bulb and a 00 W, 00 V bulb are connected in series and the voltage of 400 V is applied across the series connected bulbs, Under this condition a) 00 W bulb will be brighter than 00 W bulb b) 00 W bulb will be brighter than 00 W bulb c) Both the bulbs will have equal brightness d) Both the bulbs will be darker than when they are connected across rated voltage 6. In the network shown, if one of the 4Ω resistance is disconnected, when the circuit is active, the current flowing now will a) increase very uch b) decrease c) be zero d) increase very slightly 6. For the circuit shown in figure, when V s = 0, I = 3A. When V s = 00 V, what will be the value of I? a) A b) A c) 3 A d) 4 A 64. The current I in the circuit shown in the figure is a) 3.67A b) A c) 4A d) 6A 65. In a thyristor, the agnitude of anode current will a) increase if gate current is increased b) decrease if gate current is decreased c) increase if gate current is decreased d) not change with any variation in gate current 66. For an SC, di/dt protection is achieved through the use of a) in series with SC b) L in series with SC c) L in series with SC d) LC in series with SC 67. The circuit shown in the given figure is equivalent to a load of a) 4A b) A c) A d) 7 A 63. For the linear circuit shown in figure, a) 4/3 Ω b) 8/3 Ω c) 4 Ω d) Ω 68. The eq for the circuit shown in figure is

6 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: a) 00 watts b) 5 watts c) 0 watts d) 40 watts 73. A stove eleent draws 5 A when connected to 30 V line. How long does it take to consue one unit of energy? a) 3.45 h b).6 h c).0 h d) 0.9 h a) 4.4 Ω b) 4.57 Ω c) 5.7 Ω d) 5.88 Ω 69. Calculate the voltage drop across 4.5 Ω resistance. a) 4.5 V b) 8 V c) 9 V d) 30.5 V 70. For the network shown in the figure, the value of current in 8 Ω resistor is a) 4.8 A b).4 A c).5 d). A 7. In the figure, the value of is a).5 Ω b) 5.0 Ω c) 7.5 Ω d) 0.0 Ω 7. Power consued in the given circuit is 74. The SI unit of conductivity is a) oh- b) oh/ c) ho- d) ho/ 75. A piece of oil soaked paper has been inserted between the plates of a parallel plate capacitor. Then the potential difference between the plates will a) increase b) decrease c) reain unaltered d) becoe zero 76.The current drawn by a tungsten filaent lap is easured by an aeter. The aeter reading under steady state condition will be the aeter reading when the supply is switched on. a) sae as b) less than d) greater than d) double 77. Tesla is sae as a) Weber/eter b) Weber/(eter) c) Farad/eter d) Henry/(eter) 78. The unit of volue resistivity is a) oh- 3 / b) oh- / c) oh-gra-/gra d) oh- 4 / Four resistance Ω, 4Ω, 5 Ω, 0 Ω are connected in parallel. Their cobined resistance is a) Ω b) Ω c) 4 Ω d) 5 Ω 80.Two wires A and B have the sae crosssection and are ade of the sae aterials. A =00 Ω and b =0 Ω The nuber of ties A is longer than B is: a) 5 b) 6 c) d) 4 8. The power factor of an a.c. circuit is given by: X a) b) L Z c) d) Z X L

7 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: 8. Two 00 W, 00 V laps are connected in series across a 00 V supply. The total power consued in watts: a) 00 b) 5 c) 50 d) The Biot-Savart s law is a general odification of: a) Faraday s laws b) Kirchhoff s law c) Lenzs law d) Apere s law 84. The active and reactive power of an inductive circuit are 60 W and 80 VA respectively. The power factor of the circuit is: a) 0.8 lag b) 0.5 lag c) 0.6 lag d) 0.75 lag 85.The terinal where three or ore branches eet is known as: a) esh b) node c) terinus d) loop 86. In dc choppers, the wavefor for input and output voltages are respectively a) discontinuous, continuous b) continuous, discontinuous c) both continuous d) both discontinuous 87. A step-up chopper has V s as the source voltage and as the duty cycle. The output voltage for this chopper is given by a) V ( ) b) V /( ) s c) V ( ) d) V /( ) s 88. If resistance is 0Ω and inductance is H in a L series circuit, then tie constant of this circuit will be: a) 00 s b) 0.00 s c) 0. s d) 0 s 89. The utual inductance between two unity coupled coils of 9 H and 4 H will be: a) 36 H b). H c) 6 H d) 3H 90. The efficiency norally obtained in a circuit under the conditions of axiu power transfer is: a) 00% b)5% c) 50% d) 75% s s 9. Three resistors, each of are connected in star. What is the value of equivalent delta connected resistors? a) 3 Ω b) Ω c) Ω d) 3 Ω 9. If0F capacitor is connected to a voltage source with v( t) 50sin 000tV, then the current through the capacitor is A. a) 0 6 cos000t 4 b) 5 0 cos000t c) cos 000t d) 500 cos000t 93. In a series resonance circuit, the ipedance at half power frequencies is: a) b) c) d) 94. A circuit with a resistor, inductor and capacitor in series is resonant of f o Hz. If all the coponent values are now doubled the new resonant frequency is: fo a) 4 c) f o b) f o fo d) 95. A c long coil has 0 turns and carries a current of 750 A. The agnetising force of the coil is: a) 375 AT/ b) 5 AT/ c) 675 AT/ d) 450 AT/ 96. The rated voltage of a 3-phase power syste is given as: a) peak line to line voltage b) rs phase voltage c) peak phase voltage d) rs line to line voltage 97. The voltage wave v V sin( t 5 ) volts is applied across an ac circuit. If the current leads the voltage by0 and the axiu value of current is I, then the equation of current is

8 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: a) i I sin( t 5 ) aps b) i I sin( t 5 ) aps c) i I sin( t 5 ) aps d) i I sin( t 5 ) aps 98. The average value of current (I av ) of a sinusoidal wave of peak value (I ) is I a) I av b) I av I I c) I av I d) I av 99. The ef induced in a coil is given by d e N dt Where e is the ef induced, N is the nuber of turns and d is the instantaneous flux linkage with the coil in tie dt. The negative sign in the expression is due to a) Hans Christian Oersted b) Andre-Marie Apere c) Michale Faraday d) Eil Lenz 00. The utual inductance between two coils having self inductances 3 henry and coupling coefficient 0.85 is a).75 henry b).55 henry c) 0.45 henry d).7 henry

9 Class Centre-Pithuwala Karanpur; HO: Shila bypass road near Governent polytechnic Pithuwala Dehradun Mob: , Web: UKSSSC ANS-KEY PAPE- 3 [07]. b. b 3. d 4. a 5. c 6. b 7. c 8. d 9. d 0. b. c. c 3. a 4. b 5. a 6. b 7. c 8. c 9. c 0. a. c. b 3. a 4. d 5. a 6. d 7. c 8. b 9. b 30. c 3. c 3. a 33. b 34. b 35. c 36. d 37. b 38. c 39. a 40. b 4. d 4. b 43. c 44. d 45. b 46. d 47. c 48. a 49. b 50. c 5. c 5. b 53. d 54. a 55. c 56. d 57. a 58. b 59. b 60. d 6. b 6. a 63. b 64. b 65. b 66. c 67. d 68. a 69. d 70. c 7. c 7. c 73. c 74. b 75. d 76. c 77. a 78. c 79. b 80. c 8. c 8. b 83. b 84. c 85. d 86. a 87. b 88. c 89. a 90. a 9. a 9. d 93. b 94. a 95. c 96. b 97. a 98. c 99. a 00.d