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