19 Jun 2025 Electrician 1st sem – NSQF – Module 6 – AC circuits mock Test by admin | posted in: Uncategorized | 0 0% Question 1 of 44 1. What is the line voltage in 3 phase system if the phase voltage is 240V? 415 Volt 380 Volt 400 Volt 440 Volt Loading... Question 1 of 44Question 2 of 44 2. What is the formula to calculate the line current (IL) of this single phase R - C parallel circuit? IL = IR + IC IL = √(IR² - IC²) IL = √(IR² + IC²) IL = IR - IC Loading... Question 2 of 44Question 3 of 44 3. What is the P.F if one of the wattmeters reading is zero and the other reads total power in 2 wattmeter method of 3 phase power measurement? Zero 0.5 Unity Below 0.5 Loading... Question 3 of 44Question 4 of 44 4. Calculate the impedance of the circuit R = 5Ω, XL= 36Ω and XC = 24 Ω. 13 Ω 65 Ω 69 Ω 12 Ω Loading... Question 4 of 44Question 5 of 44 5. Which formula is used to calculate Form factor (Kf)? Kf = Average value/Effective value Kf = Effective value/Average value Kf = Maximum value/Average value Kf = Maximum value/Effective value Loading... Question 5 of 44Question 6 of 44 6. What is the phase displacement between phases in a 3 phase circuit? 120° 90° 360° 180° Loading... Question 6 of 44Question 7 of 44 7. Calculate the power factor of R.L.C circuit having resistance (R) = 15Ω, resultant reactance (X) = 20Ω connected across 240V /50Hz AC supply? 0.6 0.5 0.7 0.8 Loading... Question 7 of 44Question 8 of 44 8. What is the unit of susceptance? Ohm Mho Henry Farad Loading... Question 8 of 44Question 9 of 44 9. What is the resistance of the inductive coil takes 5A current across 240V, 50Hz supply at 0.8 power factor? 38.4Ω 48 Ω 26.6Ω 42.5Ω Loading... Question 9 of 44Question 10 of 44 10. What relationship is illustrated in between the current and voltage? Current lags behind the voltage Current and voltage are "in phase" Current leads ahead of the voltage Current and voltage are in out of phase Loading... Question 10 of 44Question 11 of 44 11. What is the main cause for below 0.5 lagging power factor in 3 phase system? Reactive power due to more inductive load Reactive power due to more capacitive load True power due to resistive load Due to fluctuation of voltage Loading... Question 11 of 44Question 12 of 44 12. What is the power factor if one of the wattmeter gives negative reading in two wattmeter method of 3 phase power measurement? Unity 0 0.5 Less than 0.5 Loading... Question 12 of 44Question 13 of 44 13. What is the power factor in a 3 phase power measurement of two wattmeters showing equal readings? 0 0.5 1 0.8 Loading... Question 13 of 44Question 14 of 44 14. What is the relation between the line current (IL) and phase current (IP) in delta connected system? IL = 3 IP IL = √3 IP IL = IP /√3 IL = IP Loading... Question 14 of 44Question 15 of 44 15. Calculate the apparent power of a star connected 3 phase load, if it is connected across 3 phase 415volt/50Hz supply at 0.8 p.f and the phase current is 10 Amps. 7.188 KVA 12.45 KVA 57.50 KVA 3.320 KVA Loading... Question 15 of 44Question 16 of 44 16. Which electrical term is defined as the total opposition to current in AC parallel circuit? Impedance Resistance Susceptance Admittance Loading... Question 16 of 44Question 17 of 44 17. What is the formula for Reactive Power (Pr) in an AC circuit? Pr = VI sin θ Pr = VI cos θ Pr = √2 VI Pr = VI Loading... Question 17 of 44Question 18 of 44 18. Which quantity is rotating at a constant angular velocity? Phasor quantity Vector quantity Scalar quantity Algebraic quantity Loading... Question 18 of 44Question 19 of 44 19. What is the phase displacement in a single phase AC circuit? 90° 120° 180° 270° Loading... Question 19 of 44Question 20 of 44 20. What is the reciprocal of inductance in AC parallel circuit? Susceptance Conductance Reactance Admittance Loading... Question 20 of 44Question 21 of 44 21. In a 3 phase system, if the active power is 4 kw and the apparent power is 5 KVA, calculate the reactive power? 2 KVAR 1 KVAR 4 KVAR 3 KVAR Loading... Question 21 of 44Question 22 of 44 22. How the resonance frequency (fr) can be increased in A.C series circuit? Increasing the inductance value Reducing the capacitance value Increasing the capacitance value Increasing the value of resistance Loading... Question 22 of 44Question 23 of 44 23. Which AC circuit contains the phase relation between voltage (V) and current (I)? Resistance and capacitance circuit Resistance, inductance and capacitance circuit Pure resistive circuit Resistance and inductance circuit Loading... Question 23 of 44Question 24 of 44 24. Calculate the apparent power in KVA of 3 phase 415V, 50 Hz, star system, if the line current (IL) is 16A at 0.8 power factor. 9.2 KVA 15.2 KVA 11.5 KVA 5.3 KVA Loading... Question 24 of 44Question 25 of 44 25. Calculate the line current of the 3 phase 415V 50 HZ supply for the balanced load of 3000 watt at 0.8 power factor is connected in star. 8.5 A 5.2 A 4.5 A 3.4 A Loading... Question 25 of 44Question 26 of 44 26. Calculate the value admittance (Y) of the RLC parallel circuit connected across 240volts/50Hz AC supply and 8 Amp. Current is passed through it? 0.33 Mho 0.003 Mho 0.033 Mho 3.33 Mho Loading... Question 26 of 44Question 27 of 44 27. What is the formula to find 3 phase Reactive power (PR) if the line voltage is 'VL' and line current is 'IL'? Pr = √3 VL IL Pr = VL IL Pr = √3 VL IL Cosθ Pr = √3 VL IL Sinθ Loading... Question 27 of 44Question 28 of 44 28. How the low power factor (P.F) can be improved in AC circuits? By connecting capacitors in series By connecting resistors in series By connecting inductors in series By connecting capacitors in parallel Loading... Question 28 of 44Question 29 of 44 29. What is the formula to calculate the three phase active power (P) if the line voltage (VL) and line current is IL and phase angle is 'θ'? P = √3 VL IL Cosθ P = √3 VL IL Sinθ P = 3 VL IL Sinθ P = 3 VL IL Cosθ Loading... Question 29 of 44Question 30 of 44 30. In which condition resonance will occur in R-L-C series circuit? Inductive reactance (XL) is less than capacitive reactance (XC) Inductive reactance (XL) is equal to capacitive reactance (XC) Inductive reactance (XL) is greater than capacitive reactance (XC) Inductive reactance (XL) is zero Loading... Question 30 of 44Question 31 of 44 31. What is the maximum value of voltage for 240 volt RMS? 376.8V 415V 339.5V 240V Loading... Question 31 of 44Question 32 of 44 32. What is the relation between the line voltage (VL) and phase voltage (Vp) in star connected system? VL = Vp VL = √3 Vp VL = 3 Vp VL = Vp/√3 Loading... Question 32 of 44Question 33 of 44 33. How will you obtain positive reading in the wattmeter reads negative reading during 3-phase two wattmeter method? By disconnecting the connection of current coil in meter By interchanging the connections of input terminals By reversing the connection of pressure coil in meter By reversing the pressure coil and current coil connection in meter Loading... Question 33 of 44Question 34 of 44 34. Which formula is used to calculate the impedance (z) of a RLC series circuit? Z = R + (XL - XC) Z = R + (XC - XL) Z = √(R² + (XC - XL)²) Z = √(R² + (XL - XC)²) Loading... Question 34 of 44Question 35 of 44 35. What is the formula to calculate the impedance (Z) of the R.L.C series circuit, if the inductive reactance (XL) is less than capacitive rectance (XC)? Z = R + (XL - XC) Z = √(R² + (XL - XC)²) Z = R + (XC - XL) Z = √(R² + (XC - XL)²) Loading... Question 35 of 44Question 36 of 44 36. What will be the readings of two watt meters (W1& W2) in 3 phase power measurement, if the power factor is zero? W1 is equal to W2 but with opposite signs Zero W1 is Positive reading, and W2 is negative reading W1 & W2 both are positive reading W1 is Positive and W2 is negative reading Loading... Question 36 of 44Question 37 of 44 37. What is the purpose of phase sequence meter? To ensure the correct phase sequence of 3 phase system To protect motor against short circuit fault To indicate the incorrect phase sequence of 3 phase To control the speed of 3 phase motor Loading... Question 37 of 44Question 38 of 44 38. What is the current in neutral conductor in 3 phase unbalanced load in star connected system? Lesser than the lowest current in any one of the phases The algebraic sum of current in 3 phases The algebraic sum of current in 2 phases only No current will flow Loading... Question 38 of 44Question 39 of 44 39. What is the condition for resonance in RLC series circuit? (Inductive reactance = 'XL', Capacitive reactance = 'XC') XL > √2 XC XL = XC XL > XC XL < XC Loading... Question 39 of 44Question 40 of 44 40. What is the form factor (Kf) for sinusoidal AC? 4.44 1.00 2.22 1.11 Loading... Question 40 of 44Question 41 of 44 41. Calculate the total power by two wattmeter (W1 & W2) method, if one of the wattmeter (W2) reading is taken after reversing. W1 + W2 W1 only W1 x 2 W1 - W2 Loading... Question 41 of 44Question 42 of 44 42. Calculate the power factor of coil having resistance of 24Ω, draws the current of 5A, at 240V/ 50Hz AC supply. 0.6 0.5 0.8 0.3 Loading... Question 42 of 44Question 43 of 44 43. In which 3 phase system, the artificial neutral is required to measure the phase voltage? 4 wire star connected system 4 wire delta connected system 3 wire star connected system 3 wire delta connected system Loading... Question 43 of 44Question 44 of 44 44. Which condition is called as resonance RLC circuit? XL > XC R < XL XL = XC XC > XL Loading... Question 44 of 44 Loading...
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