1) Two waves of the same frequency have opposite phase when the phase angle between them is_________? a. 360° b. 180° c. 90° d. 0°
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2) The power consumed in a circuit element will be least when the phase difference between the current and voltage is________? a. 180″ b. 90° c. 60° d. 0°
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3) For the same peak value, which of the following wave has the least mean value ? a. half wave rectified sine wave b. triangular wave c. sine wave d. square wave
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4) The r.m.s. value and mean value is the same in the case of___________? a. triangular wave b. sine wave c. square wave d. half wave rectified sine wave
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5) Form factor for a sine wave is________? a. 1.414 b. 0.707 c. 1.11 d. 0.637
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6) For a sine wave with peak value Imax the r.m.s. value is_______? a. 0.5 Imax b. 0.707 c. 0.9 d. 1.414 Lmax
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7) For a sine wave with peak value Emax _______ 8.30. the average value is? a. 0.636 Emax b. 0.707 Emax c. 0.434 EWc d. lAUEmax
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8) Form Factor is the ratio of__________? a. average value/r.m.s. value b. average value/peak value c. r.m.s. value/average value d. r.m.s. value/peak value
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9) The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of_______degrees? a. 90 b. 60 c. 45 d. 30
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10) Capacitors for power factor correction are rated in_________? a. kW b. kVA c. kV d. kVAR
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11) For a frequency of 200 Hz, the time period will be__________? a. 0.05 s b. 0.005 s c. 0.0005 s d. 0.5 s
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12) Capacitive reactance is more when_______? a. capacitance is less and frequency of supply is less b. capacitance is less and frequency of supply is more c. capacitance is more and frequency of supply is less d. capacitance is more and frequency of supply is more
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13) Time constant of an inductive circuit___________? a. increases with increase of inductance and decrease of resistance b. increases with the increase of inductance and the increase of resistance c. increases with decrease of inductance and decrease of resistance d. increases with decrease of inductance and increase of resistance
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14) Poor power factor________? a. reduces load handling capability of electrical system b. results in more power losses in the electrical system c. overloads alternators, transformers and distribution lines d. results in more voltage drop in the line e. results in all above
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15) In series resonant circuit, increasing inductance to its twice value and reducing capacitance to its half value__________? a. will change the maximum value of current at resonance b. will change the resonance frequency c. will change the impedance at resonance frequency d. will increase the selectivity of the circuit
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16) Inductance affects the direct current flow__________? a. only at the time of turning off b. only at the time of turning on c. at the time of turning on and off d. at all the time of operation
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17) In a highly capacitive circuit the__________? a. apparent power is equal to the actual power b. reactive power is more than the apparent power c. reactive power is more than the actual power d. actual power is more than its reactive power
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18) Inductance of a coil Varies__________? a. directly as the cross-sectional area of magnetic core b. directly as square of number of turns c. directly as the permeability of the core d. inversely as the length of the iron path e. as A. to (d)
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19) Pure inductive circuit____________? a. consumes some power on average b. does not take power at all from a line c. takes power from the line during some part of the cycle and then returns back to it during other part of the cycle d. none of the above
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20) Power factor of the following circuit will be zero__________? a. resistance b. inductance c. capacitance d. both B. and C.
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