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