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