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