MCQ – AC Fundamentals Results #1. In a pure inductor the voltage wave form leads the current by...? 90* 90* 180* 180* 60* 60* 120* 120* #2. The form factor of sinusoidal wave form is....? 1.11 1.11 1.414 1.414 3.14 3.14 1.57 1.57 #3. The instataneous voltage across a pure resistor is.... with current? lags lags out of phase out of phase in phase in phase leads leads #4. The reciprocal of frequency is known as....? time period time period amplitude amplitude time constant time constant resonance resonance #5. Reactive power is given by....? VI VI VI Cos$ VI Cos$ VIR VIR VI Sin $ VI Sin $ #6. Form factor is the ratio of....? rms value / average value rms value / average value average value / rms value average value / rms value average value x rms value average value x rms value instantaneous value x rms value instantaneous value x rms value #7. The power factor of the inductive loading is....? unity unity leading leading zero zero lagging lagging #8. Impedance at series resonance circuit is....? average average minimum minimum maximum maximum none of the above none of the above #9. Power factor is defined as....? kVA/kW kVA/kW kVAR/kVA kVAR/kVA kW/kVA kW/kVA kW/kVR kW/kVR #10. In a AC series circuits Q factor is....? 1/sin$ 1/sin$ 1/cos$ 1/cos$ sin$ sin$ cos$ cos$ #11. Power factor of R-C series circuit is.....? 0 0 greater than 1 greater than 1 1 1 between 0 and 1 between 0 and 1 #12. Capacitive reactance is......? independent of frequency independent of frequency directly proportional to capacitance directly proportional to capacitance inversely proportional to frequency inversely proportional to frequency directly proportional to frequency directly proportional to frequency #13. The ratio of Z/R is.....? reciprocal of power factor reciprocal of power factor reciprocal of form factor reciprocal of form factor power factor power factor form factor form factor #14. Admittance is the reciprocal of....? susceptance susceptance resistance resistance reactance reactance impedence impedence #15. The power factor of ordinary electric bulb is...? zero zero slightly less than one slightly less than one slightly more than one slightly more than one one one #16. Unit of inductive reactance is....? ohm ohm hentry hentry weber weber milli hentry milli hentry #17. Peak factor of a sinusoidal wave form is....? 1.41 1.41 1 1 1.21 1.21 1.11 1.11 #18. The rms value of a sine wave is 100A. Its peak value is...? 100 A 100 A 200 A 200 A 141 A 141 A 160 A 160 A #19. The power factor of an AC circuit is equal to.....? one one sine of the phase angle sine of the phase angle unity for a resistive circuit unity for a resistive circuit cosine of the phase angle cosine of the phase angle #20. Unit of reactive power is....? watt watt VAR VAR ohm ohm VA VA #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....? one half one half decrease decrease same same increase increase #23. Q factor of a series R-L-C circuit possessing resonant frequency of 10 Hz and band width of 5 Hz is...? 5.5 5.5 2 2 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 series series parallel parallel #25. Form factor of a full rectified sine wave is...? 1 1 1.571 1.571 1.41 1.41 1.11 1.11 #26. Form factor of a half rectified sine wave is...? 1.571 1.571 1.41 1.41 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? 24 A 24 A 14.14 A 14.14 A 15 A 15 A 10 A 10 A 14.14/1.4 = 10A #28. The ratio of maximum value to the rms value of an alternating quantity is called....? average value average value peak factor peak factor form factor form 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....? 90 ohms 90 ohms 70 ohms 70 ohms 40 ohms 40 ohms 50 ohms 50 ohms Root of 900 1600 = 50 #30. The unit of capacitance is....? hentry hentry ohm ohm watt watt farad farad #31. Two capacitors of 8 micro farad each are connected in series. the total capacitance is....? 16 mF 16 mF 4 mF 4 mF 10 mF 10 mF 8 mF 8 mF 8/2=4 #32. Capacitance is not affected by...? plate area plate area frequency frequency distance between plates distance between plates dielectric material dielectric material #33. Two capacitors of 10 micro farad each are connected in parallel. the total capacitance is....? 100 mF 100 mF 20 mF 20 mF 10 mF 10 mF 5 mF 5 mF #34. The capacitors opposition to alternating current is called...? capacitance capacitance resistance resistance impedence impedence capacitive reactance capacitive reactance #35. In a capacitive AC circuit is the.....? none of the above none of the above current leads voltage current leads voltage current laggs voltage current laggs voltage current is inphase with voltage current is inphase with 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....? same as the phase voltage same as the phase voltage Thrice as phase voltage Thrice as phase voltage none of these none of these Twice as phase voltage Twice as phase voltage #38. The line current in three phase star connection is....? Twice as phase current Twice as phase current Thrice as phase current Thrice as phase current none of these none of these same as the phase current same as the phase current #39. Potential inside a hollow sphere charged with a voltage V is....? 0 0 2V 2V V/2 V/2 V V #40. The reciprocal of impedance is...? admittance admittance conductance conductance susceptance susceptance resistance resistance #41. Phase sequence is the order of attaining? Maximum value Maximum value RMS value RMS value Average value Average value None of the above None of the above #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 BRY,RYB BRY,RYB RYB,YBR RYB,YBR RYB,RBY RYB,RBY #44. In a RLC resonant circuit magnification is.....? Z Z WL/R WL/R WL WL WLC WLC #45. Three phase inter connection used in 3 phase 4 wire distribution system is.....? delta delta delta delta star star star star star star delta delta finish
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