1P AC Circuits Practice Questions with Solutions – Electrical Engineering (Page 3)

#41📜 EE Pre-Board August 2014📘 PowerhouseEasy

An inductor supplied with 100V ac with a frequency of 10kHz passes a current of 10mA. The value of inductor is

A1.7 mH

B16 mH

C1 mH

D160 Mh

#42📜 EE Pre-Board March 2015📘 PowerhouseEasy

The net reactance in a series RLC circuit is

A\(X_L\)

B\(X_C\)

C\(X_C + X_L\)

D\(X_L - X_C\)

#43📜 EE Pre-Board March 2015📘 PowerhouseEasy

What is the power given \(v = 4\sin 3t\) and \(i = 4\sin 3t\)?

A\(16\sin(3t)^2\)

B\(16\sin^2(3t)\)

C\(8(1 - 6\cos 3t)\)

D\(16(1 - 6\cos 3t)\)

#44📜 EE Pre-Board March 2015📘 PowerhouseEasy

An inductance of 20 mH is connected in parallel with a capacitance of 80 μF. What is the frequency when \(X_L = X_C\)?

A100 HZ

B150 HZ

C128.5 HZ

D125.8 HZ

#45📜 EE Pre-Board March 2015📘 PowerhouseHard

A coil of 50-ohm resistance and 150 mH inductance is connected in parallel with a 50 μF capacitor. What is the power factor of the circuit?

A70% lagging

B70% leading

C80% lagging

D80% leading

#46📜 EE Pre-Board March 2015📘 PowerhouseEasy

The apparent power supplied to a load in an ac circuit is 2,000 volt- amperes with a power factor of 0.6 lagging. The reactive power is most nearly:

A1,200 VAR

B3,333 VAR

C1,600 VAR

D2,500 VAR

#47📜 EE Pre-Board March 2015📘 PowerhouseMedium

A 200 μH coil has a Q of 250 at a resonance frequency of 800 kHz. What is the effective resistance of the coil?

A1 Ω

B2 Ω

C4 Ω

D8 Ω

#48📜 EE Pre-Board March 2015📘 PowerhouseEasy

Which wqave form will have the minimum rms value if they have the same peak value of voltage?

ASquare wave

BSine wave

CTriangular Wave

DFull wave rectified sine wave

#49📜 EE Pre-Board March 2015📘 PowerhouseMedium

A 50 Ω resistance is connected in series with a coil having 25 Ω resistance and 150 mH inductance. The circuit is connected to a voltage source of \(200\sin\omega t\). Calculate the instantaneous current.

A\(2.9\sin\omega t\)

B\(2.1\sin(\omega t - 37^\circ)\)

C\(1.7\sin(\omega t - 37^\circ)\)

D\(5.11\sin(\omega t - 37^\circ)\)

#50📜 EE Pre-Board March 2015📘 PowerhouseEasy

A coil having a resistance of 3 Ω and an inductance of 0.01 H is connected in series with a capacitor across a voltage source of 220 volts. What must be the capacitance of the capacitor in order that maximum current occurs at 60 Hz?

A3.77 μF

B703.6 μF

C0.03 μF

D512.45 μF

#51📜 EE Pre-Board August 2015📘 PowerhouseMedium

Three impedances \(Z_1 = 2.2 + j2.2\), \(Z_2 = 10 + j10\) and \(Z_3 = -j5\) are connected in series. The voltage across \(Z_1\) is \(26.59 - j4.69\) V. What is the total voltage?

A93 + j62.4 V

B93 − j62.4 V

C112 + j51 V

D112 − j51 V

#52📜 EE Pre-Board August 2015📘 PowerhouseEasy

Sparking occurs when a load is switched off because the circuit has high

ACapacitance

BInductance

CResistance

DImpedance

#53📜 EE Pre-Board August 2015📘 PowerhouseEasy

What is the ac current in a circuit if the impedance is (5 + j4) Ω and the voltage source, \(V_{rms}\), is 10 V?

A\(2.04\angle 38.7^\circ\) A

B\(1.56\angle -38.7^\circ\) A

C\(1.25\angle 54.3^\circ\) A

D\(1.11\angle -42.6^\circ\) A

#54📜 EE Pre-Board August 2015📘 PowerhouseEasy

If the capacitance in a series RLC ac circuit increases by a factor of 4, what happens to the resonant frequency?

AIt doubles

BIt stays the same

CIt decreases by 50%

DIt increases by 50%

#55📜 EE Pre-Board August 2015📘 PowerhouseEasy

In a series RL circuit, R = 20 Ω and L = 0.06 H. The current lags the voltage by 80°. Determine ω.

A1,890 rad/sec

B328 rad/sec

C1,980 rad/sec

D823 rad/sec

#56📜 EE Pre-Board August 2015📘 PowerhouseEasy

An alternating current is represented by \(i = 70.7\sin 520t\). Determine the value of the current 0.0015 second after passing through zero and increasing positively.

A49.7 A

B0.96 A

C24.8 A

D74.9 A

#57📜 EE Pre-Board August 2015📘 PowerhouseEasy

A complex current wave is represented by the equation \(i = 5 + 5\sin(120\pi t)\) A. Find its average value in amperes.

A4.5

B6

C5

D4

#58📜 EE Pre-Board August 2015📘 PowerhouseEasy

If resonant frequency is 10kHz and quality factor is 50, then

ABandwidth is 200 Hz

BXL=50,000 Ω

CR= 50 Ω

DXc= 50,000 Ω

#59📜 EE Pre-Board March 2016📘 PowerhouseEasy

For an RL circuit, the power factor cannot be less than ______ or greater than _____.

A0,1

B1,0

C0, -1

D-1, 0

#60📜 EE Pre-Board March 2016📘 PowerhouseEasy

In a given circuit, when the power factor is unity, the reactive power is

AMaximum

Bequal to \(I^2R\)

Czero

Dminimum

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