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