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