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