MCQ – AC Fundamentals Results #1. In a pure inductor the voltage wave form leads the current by...? 90* 90* 60* 60* 120* 120* 180* 180* #2. The form factor of sinusoidal wave form is....? 1.11 1.11 1.414 1.414 1.57 1.57 3.14 3.14 #3. The instataneous voltage across a pure resistor is.... with current? in phase in phase out of phase out of phase leads leads lags lags #4. The reciprocal of frequency is known as....? time period time period resonance resonance amplitude amplitude time constant time constant #5. Reactive power is given by....? VI Cos$ VI Cos$ VI VI VI Sin $ VI Sin $ VIR VIR #6. Form factor is the ratio of....? average value x rms value average value x rms value average value / rms value average value / rms value instantaneous value x rms value instantaneous value x rms value rms value / average value rms value / average value #7. The power factor of the inductive loading is....? leading leading unity unity zero zero lagging lagging #8. Impedance at series resonance circuit is....? minimum minimum none of the above none of the above average average maximum maximum #9. Power factor is defined as....? kW/kVR kW/kVR kW/kVA kW/kVA kVA/kW kVA/kW kVAR/kVA kVAR/kVA #10. In a AC series circuits Q factor is....? sin$ sin$ 1/cos$ 1/cos$ 1/sin$ 1/sin$ cos$ cos$ #11. Power factor of R-C series circuit is.....? 0 0 between 0 and 1 between 0 and 1 greater than 1 greater than 1 1 1 #12. Capacitive reactance is......? directly proportional to capacitance directly proportional to capacitance inversely proportional to frequency inversely proportional to frequency directly proportional to frequency directly proportional to frequency independent of frequency independent of frequency #13. The ratio of Z/R is.....? form factor form factor power factor power factor reciprocal of form factor reciprocal of form factor reciprocal of power factor reciprocal of power factor #14. Admittance is the reciprocal of....? susceptance susceptance impedence impedence resistance resistance reactance reactance #15. The power factor of ordinary electric bulb is...? zero zero slightly less than one slightly less than one one one slightly more than one slightly more than one #16. Unit of inductive reactance is....? milli hentry milli hentry hentry hentry ohm ohm weber weber #17. Peak factor of a sinusoidal wave form is....? 1.11 1.11 1 1 1.21 1.21 1.41 1.41 #18. The rms value of a sine wave is 100A. Its peak value is...? 200 A 200 A 100 A 100 A 160 A 160 A 141 A 141 A #19. The power factor of an AC circuit is equal to.....? one one cosine of the phase angle cosine of the phase angle sine of the phase angle sine of the phase angle unity for a resistive circuit unity for a resistive circuit #20. Unit of reactive power is....? ohm ohm VA VA watt watt VAR VAR #21. With in the increase in applied frequency, the dielectric loss will be....? decrease decrease same same one half one half increase increase #22. With in the increase in applied frequency, the dielectric loss will be....? increase increase one half one half decrease decrease same same #23. Q factor of a series R-L-C circuit possessing resonant frequency of 10 Hz and band width of 5 Hz is...? 2 2 2.5 2.5 4 4 5.5 5.5 #24. Power factor of an inductive circuit is usually improved by adding a capacitor to it in....? series series parallel parallel either in series or parallel either in series or parallel #25. Form factor of a full rectified sine wave is...? 1.11 1.11 1.41 1.41 1.571 1.571 1 1 #26. Form factor of a half rectified sine wave is...? 1.41 1.41 1.571 1.571 1 1 1.11 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? 10 A 10 A 15 A 15 A 24 A 24 A 14.14 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 form factor average value average value peak factor peak factor mean value mean value #29. A seris RL circuit has a resistance of 30 ohms and an inductance of 40 ohms. The impedence is....? 70 ohms 70 ohms 50 ohms 50 ohms 40 ohms 40 ohms 90 ohms 90 ohms Root of 900 1600 = 50 #30. The unit of capacitance is....? hentry hentry farad farad watt watt ohm ohm #31. Two capacitors of 8 micro farad each are connected in series. the total capacitance is....? 8 mF 8 mF 10 mF 10 mF 4 mF 4 mF 16 mF 16 mF 8/2=4 #32. Capacitance is not affected by...? distance between plates distance between plates dielectric material dielectric material plate area plate area frequency frequency #33. Two capacitors of 10 micro farad each are connected in parallel. the total capacitance is....? 20 mF 20 mF 5 mF 5 mF 10 mF 10 mF 100 mF 100 mF #34. The capacitors opposition to alternating current is called...? resistance resistance capacitive reactance capacitive reactance capacitance capacitance impedence impedence #35. In a capacitive AC circuit is the.....? none of the above none of the above current is inphase with voltage current is inphase with voltage current leads voltage current leads voltage current laggs voltage current laggs voltage #36. Which condition is called as resonance RLC circuit? XL > XC XL > XC XL= XC XL= XC XL< XC XL< XC #37. The line voltage in three phase delta connection is....? Thrice as phase voltage Thrice as phase voltage Twice as phase voltage Twice as phase voltage same as the phase voltage same as the phase voltage none of these none of these #38. The line current in three phase star connection is....? none of these none of these Thrice as phase current Thrice as phase current Twice as phase current Twice as phase current same as the phase current same as the phase current #39. Potential inside a hollow sphere charged with a voltage V is....? V V 0 0 V/2 V/2 2V 2V #40. The reciprocal of impedance is...? admittance admittance resistance resistance conductance conductance susceptance susceptance #41. Phase sequence is the order of attaining? None of the above None of the above Maximum value Maximum value RMS value RMS value Average value Average value #42. In a R.L.C series resonant circuit....? R=XC R=XC R=XL R=XL R=Z R=Z XL>XC XL>XC #43. Two possible phase sequences are....? RBY,YRB RBY,YRB RYB,YBR RYB,YBR BRY,RYB BRY,RYB RYB,RBY RYB,RBY #44. In a RLC resonant circuit magnification is.....? Z Z WLC WLC WL/R WL/R WL WL #45. Three phase inter connection used in 3 phase 4 wire distribution system is.....? delta delta delta delta delta delta star star star star star star finish
Recent Comments