MCQ – AC Fundamentals Results #1. In a pure inductor the voltage wave form leads the current by...? 60* 60* 180* 180* 120* 120* 90* 90* #2. The form factor of sinusoidal wave form is....? 1.11 1.11 3.14 3.14 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 lags lags out of phase out of phase #4. The reciprocal of frequency is known as....? time constant time constant resonance resonance time period time period amplitude amplitude #5. Reactive power is given by....? VI VI VI Sin $ VI Sin $ VI Cos$ VI Cos$ VIR VIR #6. Form factor is the ratio of....? average value x rms value average value x rms value instantaneous value x rms value instantaneous value x rms value average value / rms value average value / rms value rms value / average value rms value / average value #7. The power factor of the inductive loading is....? lagging lagging zero zero leading leading unity unity #8. Impedance at series resonance circuit is....? minimum minimum none of the above none of the above maximum maximum average average #9. Power factor is defined as....? kVA/kW kVA/kW kVAR/kVA kVAR/kVA kW/kVR kW/kVR kW/kVA kW/kVA #10. In a AC series circuits Q factor is....? 1/cos$ 1/cos$ cos$ cos$ 1/sin$ 1/sin$ sin$ sin$ #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......? inversely proportional to frequency inversely proportional to frequency directly proportional to frequency directly proportional to frequency independent of frequency independent of 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....? resistance resistance reactance reactance susceptance susceptance impedence impedence #15. The power factor of ordinary electric bulb is...? zero zero slightly more than one slightly more than one slightly less than one slightly less than one one one #16. Unit of inductive reactance is....? hentry hentry weber weber ohm ohm milli hentry milli hentry #17. Peak factor of a sinusoidal wave form is....? 1.11 1.11 1.41 1.41 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 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....? VA VA watt watt VAR VAR ohm ohm #21. With in the increase in applied frequency, the dielectric loss will be....? one half one half same same increase increase decrease decrease #22. With in the increase in applied frequency, the dielectric loss will be....? same same decrease decrease increase increase one half one half #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 2.5 5.5 5.5 4 4 2 2 #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 1 1.11 1.11 1.41 1.41 1.571 1.571 #26. Form factor of a half rectified sine wave is...? 1 1 1.41 1.41 1.571 1.571 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 24 A 24 A 14.14 A 14.14 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....? average value average value form factor form factor mean value mean value peak factor peak factor #29. A seris RL circuit has a resistance of 30 ohms and an inductance of 40 ohms. The impedence is....? 70 ohms 70 ohms 90 ohms 90 ohms 40 ohms 40 ohms 50 ohms 50 ohms Root of 900 1600 = 50 #30. The unit of capacitance is....? watt watt hentry hentry farad farad ohm ohm #31. Two capacitors of 8 micro farad each are connected in series. the total capacitance is....? 16 mF 16 mF 10 mF 10 mF 4 mF 4 mF 8 mF 8 mF 8/2=4 #32. Capacitance is not affected by...? distance between plates distance between plates frequency frequency plate area plate area 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...? resistance resistance capacitance capacitance impedence impedence capacitive reactance capacitive reactance #35. In a capacitive AC circuit is the.....? current is inphase with voltage current is inphase with voltage current laggs voltage current laggs voltage none of the above none of the above 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....? 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....? Twice as phase current Twice as phase current none of these none of these Thrice as phase current Thrice 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/2 V/2 0 0 V V #40. The reciprocal of impedance is...? susceptance susceptance resistance resistance admittance admittance conductance conductance #41. Phase sequence is the order of attaining? Average value Average value RMS value RMS value None of the above None of the above Maximum value Maximum 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....? RYB,YBR RYB,YBR RYB,RBY RYB,RBY BRY,RYB BRY,RYB RBY,YRB RBY,YRB #44. In a RLC resonant circuit magnification is.....? WLC WLC WL/R WL/R WL WL Z Z #45. Three phase inter connection used in 3 phase 4 wire distribution system is.....? star star delta delta delta delta star star star star delta delta finish
Recent Comments