MCQ – AC Fundamentals Results #1. 1 180* 120* 60* 90* #2. 2 3.14 1.414 1.57 1.11 #3. 3 in phase lags leads out of phase #4. 4 resonance time constant amplitude time period #5. 5 VI VI Cos$ VIR VI Sin $ #6. Form factor is the ratio of….? average value x rms value instantaneous value x rms value rms value / average value average value / rms value #7. The power factor of the inductive loading is….? zero lagging unity leading #8. Impedance at series resonance circuit is….? none of the above average minimum maximum #9. Power factor is defined as….? kW/kVR kVAR/kVA kW/kVA kVA/kW #10. In a AC series circuits Q factor is….? 1/sin$ sin$ 1/cos$ cos$ #11. Power factor of R-C series circuit is…..? between 0 and 1 1 greater than 1 0 #12. Capacitive reactance is……? independent of frequency directly proportional to capacitance directly proportional to frequency inversely proportional to frequency #13. The ratio of Z/R is…..? form factor reciprocal of power factor reciprocal of form factor power factor #14. Admittance is the reciprocal of….? reactance resistance susceptance impedence #15. The power factor of ordinary electric bulb is…? slightly less than one one zero slightly more than one #16. Unit of inductive reactance is….? weber ohm milli hentry hentry #17. Peak factor of a sinusoidal wave form is….? 1 1.41 1.11 1.21 #18. The rms value of a sine wave is 100A. Its peak value is…? 141 A 160 A 100 A 200 A #19. The power factor of an AC circuit is equal to…..? sine of the phase angle unity for a resistive circuit one cosine of the phase angle #20. Unit of reactive power is….? watt ohm VA VAR #21. With in the increase in applied frequency, the dielectric loss will be….? decrease increase same one half #22. With in the increase in applied frequency, the dielectric loss will be….? one half same decrease increase #23. Q factor of a series R-L-C circuit possessing resonant frequency of 10 Hz and band width of 5 Hz is…? 4 2 2.5 5.5 #24. Power factor of an inductive circuit is usually improved by adding a capacitor to it in….? either in series or parallel series parallel #25. Form factor of a full rectified sine wave is…? 1.41 1.571 1.11 1 #26. Form factor of a full rectified sine wave is…? 1.41 1.11 1 1.571 rms / average = (Vm/2)/(Vm/pi) = 1.571 #27. An alternating current is given by i=14.14sin377t. find its rms value of current? 24 A 15 A 14.14 A 10 A 14.14/1.4 = 10A #28. The ratio of maximum value to the rms value of an alternating quantity is called….? mean value average value peak factor form factor #29. A seris RL circuit has a resistance of 30 ohms and an inductance of 40 ohms. The impedence is….? 70 ohms 50 ohms 90 ohms 40 ohms Root of 900 1600 = 50 #30. The unit of capacitance is….? watt ohm farad hentry #31. Two capacitors of 5 micro farad each are connected in series. the total capacitance is….? 8 mF 4 mF 10 mF 16 mF 8/2=4 #32. Capacitance is not affected by…? plate area dielectric material frequency distance between plates #33. Two capacitors of 10 micro farad each are connected in parallel. the total capacitance is….? 20 mF 5 mF 10 mF 100 mF #34. The capacitors opposition to alternating current is called…? capacitance capacitive reactance impedence resistance #35. In a capacitive AC circuit is the…..? current leads voltage current laggs voltage none of the above current is inphase with voltage #36. Which condition is called as resonance RLC circuit? XL< XC XL > XC XL= XC #37. The line voltage in three phase delta connection is….? Twice as phase voltage Thrice as phase voltage none of these same as the phase voltage #38. The line voltage in three phase delta connection is….? Twice as phase current same as the phase current Thrice as phase current none of these #39. Potential inside a hollow sphere charged with a voltage V is….? V V/2 2V 0 #40. The reciprocal of impedance is…? conductance susceptance admittance resistance #41. Phase sequence is the order of attaining? RMS value Average value Maximum value None of the above #42. In a R.L.C series resonant circuit….? R=Z R=XL R=XC XL>XC #43. Two possible phase sequences are….? RBY,YRB BRY,RYB RYB,YBR RYB,RBY #44. In a RLC resonant circuit magnification is…..? WL/R WL Z WLC #45. Three phase inter connection used in 3 phase 4 wire distribution system is…..? delta star star delta delta star Previous Finish
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