This is the Multiple Choice Questions Part 8 of the Series in AC Circuits as one of the Electrical Engineering topic. In Preparation for the REE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Electrical Engineering field, Electrical Engineering Books, Journals and other Electrical Engineering References.

#### Continue Practice Exam Test Questions Part 8 of the Series

PARALLEL CIRCUITS

**Choose the letter of the best answer in each questions.**

โ MCQ in AC Circuits Part 7 | REE Board Exam

351.ย EE Board Exam April 1990

A capacitor, an electric resistance heater, andย impedance are connected in parallel to a 120ย V,ย 60 Hz system. The capacitor draws 50ย var,ย theย heater draws 100 W and the impedance coil draws 269 VA at a pf 0f 0.74 lagging. Determine the system power factor.

A.ย 0.933 leading

B.ย 0.928 lagging

C.ย 0.916 lagging

D.ย 0.911 lagging

352.ย REE Board Exam October 1996

Aย bankย of capacitors is connected in parallel each ratedย at 10 kVAR,ย 380 volts.ย If one unit is shortedย out,ย whatย would be the net capacitanceย of the bank?

A.ย 330 ฮผF

B.ย 440 ฮผF

C.ย 220 ฮผF

D.ย 110 ฮผF

Answer: **Option B**

Solution:

353.ย EE Board Exam October 1992

A capacitor of 3.18 microfarads is connected in parallel with a resistance of 2,000 ohms.ย Theย combinationย isย further connectedย inย seriesย withย an inductance of 795 mH and resistance of 100 ohms across a supply given by e = 400 sin ฯt + 80 sin (3ฯt + 60ยฐ). Assume w = 314 radians/sec. Determine the rms value of the total current.

A.ย 0.40 A

B.ย 0.33 A

C.ย 0.56 A

D.ย 0.45 A

354.ย EE Board Exam June 1990

Three loads, units A, B and C are connected in parallel and take currents that are respectively 12, 10ย and 15 Aย respectively. Assumingย I_{a} to beย the reference phasor. I_{b} leads Ia by 30ยฐ and Ic lags behind Ia by 65ยฐ, calculate the total (resultant) current.

A.ย 28.33 A

B.ย 30.21 A

C.ย 26.46 A

D.ย 32.10 A

355.ย EE Board Exam April 1992

Twoย single-phaseย motorsย areย connectedย inย parallelย acrossย aย 120-volt,ย 60-cycle source of supply. Motor A is a split-phase inductance type and motor B is a capacitor type:

Determine total power factor.

A.ย 0.886 lag

B.ย 0.864 lag

C.ย 0.817 lag

D.ย 0.825 lag

Answer: **Option B**

Solution:

356.ย EE Board Exam April 1992

A 250 V, 30 Hz generator supplies power to a parallel circuit consisting of a 20 HP motor whose efficiency is 90% at 0.80 pf lagging and a second load that draws an apparent power of 7 kVA at unity pf.ย Determineย the system power factor.

A.ย 0.828 lagging

B.ย 0.831 lagging

C.ย 0.802 lagging

D.ย 0.884 lagging

357.ย EE Board Exam April 1985

A resistance of 5 ohms is connected in series with a capacitor of 442.1 ฮผF. The combination is then connected in parallel with an inductance ofย 21.22 mH. Solve for the resultant current if the circuit is connected across a 120 V, 60 Hz AC source.

A.ย 9.44 A

B.ย 10.68 A

C.ย 11.29 A

D.ย 10.34 A

Answer: **Option D**

Solution:

Solution: Solve for the resultant current if the circuit is connected across

358.ย EE Board Exam April 1993

An inductor L_{1} is connected in series with a parallel combination of inductor L_{2}ย and capacitorย C.ย The impedance of the circuit wย =ย 400 rad/sec is j100 ohms. The circuit is to yield infinite impedance at w = 1,000 rad/sec and zero impedance at w = 2,000 rad/sec. Determine the value of C.

A.ย 1.28 ฮผF

B.ย 1.67 ฮผF

C.ย 2.06 ฮผF

D.ย 1.32 ฮผF

Answer: **Option D**

Solution:

359.ย EE Board Exam April 1992

A sinusoidalย current source, 10 cos 1000t, is in parallel both with a 20-ohm resistorย andย theย seriesย combinationย ofย aย 10-ohmย resistorย andย aย 10-mH inductor. Find the equation of the voltage across the 10 -ohm resistor.

A.ย 63.25 cos (1000t โ 18.43ยฐ)

B.ย 61.32 cos (1000t โ 20.34ยฐ)

C.ย 59.36 cos (1000t โ 17.45ยฐ)

D.ย 60.12 cos (1000t โ 19.38ยฐ)

360.ย EE Board Exam April 1993

A 1-hp, 220 V, 60 Hz capacitor-start motor has main and auxiliary winding impedance at starting of 3.5 + j2.5 ohms and 8.6 + j2.5 ohms, respectively. Determine the value of the starting capacitance that will place the main and auxiliary winding currents 90ยฐ apart at starting,

A.ย 186.75 ฮผF

B.ย 174.35 ฮผF

C.ย 182.43 ฮผF

D.ย 170.67 ฮผF

361.ย EE Board Exam October 1990

Two impedances A and B are connected in parallelย across aย 120 V ac supply. The total current and the current in each impedance is adjusted to 20 A.ย Theย power drawn by Aย is doubledย that of B andย the power factor is lagging. Determine the power factor of A.

A.ย 0.650 lagging

B.ย 0.704 lagging

C.ย 0.841 lagging

D.ย 0.677 lagging

362.ย REE Board Exam March 1998

A coil of 50-ohm resistance and of 150-mHย inductance is connected in parallel with aย 50-ฮผFย capacitor.ย Ifย the sourceย voltage is 100ย sin (ฯt + 30ยฐ), what is the equation of the line current?

A.ย 1.91 sin (ฯt + 52.5ยฐ)

B.ย 1.25 sin (ฯt + 75.5ยฐ)

C.ย 1.82 sin (ฯt – 62ยฐ)

D.ย 1.32 sin (ฯt โ 75.5ยฐ)

363.ย EE Board Exam October 1984

A resistor R is connected in parallel with a 10-ohm inductive reactance. The combination is then connected in series with a 4-ohm capacitive reactance. The whole combination is connected across a 100-volt, 60 Hz supply, How much is R if the angle between the supply voltage and the total current is 45 degrees?

A.ย 12 ohms

B.ย 25 ohms

C.ย 16 ohms

D.ย 20 ohms

Answer: **Option D**

Solution:

364.ย EE Board Exam April 1980

Three impedances Z_{1} = 1 – j4 ohms, Z_{2} = โ j6 ohms and Z_{3} = 4 + j3 ohms are connectedย inย series-parallel.ย Z_{1}ย isย connectedย inย seriesย withย theย parallel combinationย ofย Z_{2}ย andย Z_{3}.ย Determineย theย equivalentย impedanceย ofย the combination.

A.ย 4.32 โ j1.21 ohms

B.ย 2.23 โ j3.32 ohms

C.ย 6.76 โ j5.68 ohms

D.ย 5.42 โ j7.21 ohms

Answer: **Option C**

Solution:

365.ย EE Board Exam October 1984

A 5-ohm resistor is connected in parallel with a 10-ohm inductive reactance. The combination is then connected in seriesย withย aย 4-ohmย capacitive reactance. The whole combination is connectedย acrossย aย 100-volt,ย 60 Hz supply. How much is the total current drawn by the circuit?

A.ย 22.36 A

B.ย 20.45 A

C.ย 23.16 A

D.ย 19.89 A

366.ย EE Board Exam April 1983

A non-inductive resistor R is connected in parallel with an inductive reactance of 10 ohms.ย The combination isย then connected in seriesย with a capacitive reactance of 5 ohms. The whole combination is connected across aย 100-volt,ย 60ย Hz ac source. If R is equal toย 5 ohms, solveย for the voltage across the parallel combination.

A.ย 87.53 V

B.ย 88.34 V

C.ย 89.44 V

D.ย 91.87 V

367.ย EE Board Exam April 1980

Three impedances Z_{1}ย = 1ย –ย j4 ohms, Z_{2}ย =ย โย j6 ohms and Z_{3}ย = 4 + j3 ohms respectively are connected in series-parallel. Z_{1}ย is connected in series with the parallel combination of Z_{2} and Z_{3}. If this circuit is connected across a 230 V, 60 Hz source, determine the voltage across the parallel combination of Z_{2} and Z_{3}.

A.ย 156.3 V

B.ย 146.8 V

C.ย 135.7 V

D.ย 163.2 V

Answer: **Option A**

Solution:

368.ย EE Board Exam October 1980

Given three impedances: Z_{1} = 10 + j0 ohms, Z_{2} = 3 + j4 ohms and Z_{3} = 8 โ j6 ohms. Impedance Z_{2} and Z_{3} are connected in parallel and the combination is connected in series with impedance Z_{1} across a 120 V single-phase 60 Hz source. Find the total power drawn by the impedance.

A.ย 1008 W

B.ย 1204 W

C.ย 1038 W

D.ย 1103 W

369.ย EE Board Exam October 1993

If admittance Y = 0.06 โ j0.08 mho, then conductance G equals

A.ย -0.06

B.ย 0.06

C.ย 0.08

D.ย -0.08

Answer: **Option B**

Solution:

Given that admittance Y=0.06โj0.08 mho, conductance G can be calculated using the formula:

G = Real part of admittance

G=Real(Y) = 0.06 mho

370.ย EE October 1986, April 1993

A parallel circuit consists of a resistor having a conductance of 4 mhos, an inductive reactor having a susceptance of 8 mhos and a capacitive reactor having a susceptance of 5 mhos. What is the impedance of the circuit?

A.ย 0.11 + j0.13 ohms

B.ย 0.13 + j0.11 ohms

C.ย 0.12 + j0.16 ohms

D.ย 0.16 + j0.12 ohms

371.ย REE Board Exam October 1994

A capacitor branch having a ratio of X_{C} to R of 5 is paralleled with impedance consistingย ofย aย 4ย ฮฉย resistanceย andย aย 3ย ฮฉย inductiveย reactance.ย Theย power factor of the resulting circuit is 0.8 leading. Find the size of the capacitor in ฮผF if the frequency is 60 Hz.

A.ย 879.9 ฮผF

B.ย 1078.9 ฮผF

C.ย 978.9 ฮผF

D.ย 778.9 ฮผF

Answer: **Option D**

Solution:

372.ย ECE Board Exam November 2000

A parallel-LC circuit can store energy fed to it power source and produces an output which is a continuous A.C. wave. It is often called a ____.

A.ย Tank circuit

B.ย Store circuit

C.ย Storage circuit

D.ย Power circuit

Answer: **Option A**

Solution:

373.ย ECE Board Exam November 2001

What is the impedance relationship between the output of one circuit and the input of another circuit will provide maximum power transfer?

A.ย very low impedance

B.ย higher impedance

C.ย lower impedance

D.ย equal impedance

Answer: **Option D**

Solution:

374.ย The series circuit of R = 30ย ฮฉย & X = 4ย ฮฉย and a parallel circuit of Rโ and Xโ have the same impedance and power factor. Calculate the value of Rโ and Xโ.

A.ย 8.33 ฮฉ and 6.25 ฮฉ

B.ย 2.56 ฮฉ and, 3.83 ฮฉ

C.ย 7.47 ฮฉ and 7.51 ฮฉ

D.ย 5.62 ฮฉ and 9.84 ฮฉ

Answer: **Option A**

Solution:

375.ย A 25 ฮฉ resistor, 2 mH inductor and 30 ฮผF capacitor are connected in parallel across 100 sin (5000t + 45ยฐ) V source. Calculate the total current taken by the circuit.

A.ย 4 sin (5000t + 45ยฐ) + 5 cos (5000t + 45ยฐ)

B.ย 14 sin (5000t) + 15 sin (5000t + 45ยฐ)

C.ย 40 sin (5000t + 30ยฐ) + 50 cos (5000t + 45ยฐ)

D.ย 4 cos (5000t + 45ยฐ) + 5 cos (5000t + 45ยฐ)

Answer: **Option A**

Solution:

376.ย A parallel circuit with one branch of R = 5 ฮฉ and a single unknown element in the other branch has the following applied voltage and total current e = 10 cos (50t + 60ยฐ)ย V and i = 5.38 cos (50tย โย 8.23ยฐ) A. The unknown element is ______.

A.ย L = 0.04 H

B.ย L = 0.02 H

C.ย C = 10 ฮผF

D.ย C = 5 ฮผF

Answer: **Option A**

Solution:

377.ย An impedance of 3 โ j3 ฮฉ is connected in parallel with 5 + j2 ฮฉ. The voltmeter connected across 3ย ฮฉย resistance measures 45 V. Calculateย the total current of the circuit.

A.ย 22.4 A

B.ย 41.3 A

C.ย 13.4 A

D.ย 7.91 A

Answer: **Option A**

Solution:

378.ย Twoย impedancesย Z_{Aย } =ย 4ย +ย j6ย ฮฉย andย Z_{Bย } areย connectedย inย parallel.ย The apparentย powerย forย theย impedanceย Bย isย 1490ย VA.ย Determineย theย total apparent power.

A.ย 4250 VA

B.ย 3290 VA

C.ย 2652 VA

D.ย 8031 VA

Answer: **Option A**

Solution:

379.ย Aย feederย suppliesย twoย loads,ย oneย atย 50ย amperesย atย 50%ย powerย factor,ย the otherย 150ย amperesย atย unityย powerย factor.ย Theย total currentย suppliedย byย the feeder is approximately ____.

A.ย 180 A

B.ย 200 A

C.ย 175 A

D.ย 150 A

Answer: **Option A**

Solution:

380.ย Aย fluorescent lampย and its inductiveย ballastย draw a 1.0 A currentย atย 50% lagging power factor from a 120-V, 60-Hz source. What is the overall power factor when a 26.5 ฮผF capacitor is connected across the fixture?

A.ย 0.832 lagging

B.ย 0.832 leading

C.ย 0.5 leading

D.ย 0.5 lagging

Answer: **Option B**

Solution:

Solution: What is the overall power factor when a 26.5 ฮผF capacitor is connected

381.ย Ten impedances connected in parallel draw the following individual current: 5โ 0ยฐ,ย 5โ 5ยฐ, 5โ 10ยฐ,ย 5โ 15ยฐ, 5โ 20ยฐ, 5โ 25ยฐ, 5โ 30ยฐ, 5โ 35ยฐ, 5โ 40ยฐ, 5โ 45ยฐ. What is the effective value of the total current?

A.ย 48.444 A

B.ย 34.255 A

C.ย 25.345 A

D.ย 84.389 A

Answer: **Option A**

Solution:

382.ย Ten impedances connected in parallel draw the following individual current: 5โ 0ยฐ,ย 5โ 5ยฐ, 5โ 10ยฐ,ย 5โ 15ยฐ, 5โ 20ยฐ, 5โ 25ยฐ, 5โ 30ยฐ, 5โ 35ยฐ, 5โ 40ยฐ, 5โ 45ยฐ. What is the equivalent impedance that could replace the impedances if the source voltage is 100 sin 150t V?

A.ย 1.325โ -30ยฐ ฮฉ

B. 6.026โ -2.5ยฐ ฮฉ

C.ย 32.51โ 50ยฐ ฮฉ

D. 1.46โ -22,5ยฐ ฮฉ

Answer: **Option D**

Solution:

383.ย Ten impedances connected in parallel draw the following individual current:ย 5โ 0ยฐ,ย 5โ 5ยฐ, 5โ 10ยฐ,ย 5โ 15ยฐ, 5โ 20ยฐ, 5โ 25ยฐ, 5โ 30ยฐ, 5โ 35ยฐ, 5โ 40ยฐ, 5โ 45ยฐ. What is the equivalent power factor of the circuit?

A.ย 0.924

B.ย 0.866

C.ย 0.707

D.ย 0.876

Answer: **Option A**

Solution:

384.ย Ten impedances connected in parallel draw the following individual current: 5โ 0ยฐ,ย 5โ 5ยฐ, 5โ 10ยฐ,ย 5โ 15ยฐ, 5โ 20ยฐ, 5โ 25ยฐ, 5โ 30ยฐ, 5โ 35ยฐ, 5โ 40ยฐ, 5โ 45ยฐ. What element should be connected across the circuitย so that the current would be in phase with the source?

A.ย 54 mH

B.ย 25.4 mH

C.ย 13 mH

D.ย 31 mH

Answer: **Option B**

Solution:

385.ย A small single-phase, 240 V induction motor is tested in parallel with 160ย ฮฉ resistor. The motor takes 2 amperes and the total current is 3 amperes. What is the power of the whole circuit?

A.ย 800 W

B.ย 360 W

C.ย 220 W

D.ย 580 W

386.ย A capacitor is placed in parallel with two inductive loads, one of 20 A at 30ยฐ lagging and another of 40 A at 60ยฐ lagging. What current in amperes should flow in the capacitor so that the circuit will have a unity power factor?

A.ย 35.8 A

B.ย 44.6 A

C.ย 28.8 A

D.ย 50.2 A

387.ย A coil of 10 ฮฉ resistance and 0.1 H inductance is connected in parallel with a capacitor of unknown capacitance. If the total impedance of the combination is 100 ฮฉ, determine the value of the capacitance.

A.ย 50 ฮผF

B.ย 100 ฮผF

C.ย 150 ฮผF

D.ย 200 ฮผF

388.ย An impedance equal to 4.44โ 60ยฐ ฮฉ is connected across a 220 V source. What should be the value of the second impedance in parallel with the first, if the total power delivered to the circuit is to be 16.5ย kWย and the overall power factor is to be unity?

A.ย 2.21โ 30.1ยฐ ฮฉ

B.ย 3.33โ -40.9ยฐ ฮฉ

C. 5.63โ 30ยฐ ฮฉ

D.ย 6.543โ -45ยฐ ฮฉ

389.ย Anย inductive reactance of 8 ohms is connected in parallel with a capacitive reactance of 18 ohms. This combination is then connected in series with a variableย resistance.ย For what value ofย resistance willย the power factor be 0.5?

A.ย 8.314 ฮฉ

B.ย 3.318 ฮฉ

C.ย 13.81 ฮฉ

D.ย 1.381 ฮฉ

390.ย Twoย impedances Z_{1} =ย 3 + j4 and Z_{2} = 5 โ j8.66 ohms respectively are connected inย parallel.ย Ifย theย combination isย connectedย acrossย aย 240 Vย AC source, how much is the total current?

A.ย 44.4 A

B.ย 42.1 A

C.ย 40.6 A

D.ย 39.9 A

391.ย A resistance of 20 ohms and an unknown capacitanceย are connectedย in parallel across a 110 V, variable frequency AC source. When the frequency is 60 Hz, the current drawn by the circuit is 6 A. At what frequency will the current drawn fall to 5.8 A?

A.ย 42. 33 Hz

B.ย 50.12 Hz

C.ย 46.02 Hz

D.ย 44.18 Hz

392.ย Two parallel branches have admittances 0.3 +ย j0.4 and 0.2 โ j0.25ย S, respectively.ย If the current in the first branch is 10ย A,ย determine theย total current supplied to the parallel combination.

A.ย 10.44 A

B.ย 12.10 A

C.ย 15.32 A

D.ย 11.24 A

Answer: **Option A**

Solution:

Solution: Determine theย total current supplied to the parallel combination

393.ย An inductive reactance of 3 ohms is connected in parallel with a capacitive reactance of 4 ohms. If the combination is connected in series with a 4 ohm resistance, solve for the power factor of the whole combination.

A.ย 0.333

B.ย 0.409

C.ย 0.567

D.ย 0.316

Answer: **Option D**

Solution:

394.ย An R-L circuit has Z = (6 + j8) ohm. Its susceptance is ____ siemens.

A.ย 0.06

B.ย 0.08

C.ย 0.1

D.ย -0.08

395.ย The impedances of two parallel branches of a circuit are (10 + j10) and (10 โ j10) respectively. The impedance of the parallel combination is

A.ย 20 + j0

B.ย 5 โ j5

C.ย 10 + j0

D.ย 0 โ j20

396.ย Domestic appliances are connected in parallel across ac mains because

A.ย it is a simple arrangement

B.ย operation of each appliance becomes independent of each other

C.ย appliances have same current ratings

D.ย this arrangement occupies less space

Answer: **Option B**

Solution:

397.ย Whenย aย parallelย acย circuitย containsย aย numberย ofย branches,ย thenย itย is convenient to solve the circuit by

A.ย phasor diagram

B.ย phasor algebra

C.ย equivalent impedance method

D.ย none of the above

Answer: **Option B**

Solution:

398.ย The power taken by the circuit shown in Fig. 13.1 is

A.ย 470 W

B.ย 1920 W

C.ย 1200 W

D.ย none of these

Answer: **Option B**

Solution:

399.ย The active component of line current in Fig. 13.1 is

A.ย 8 A

B.ย 4 A

C.ย 5.3 A

D.ย none of these

Answer: **Option A**

Solution:

400.ย The power factor of the circuit shown in Fig. 13.1 is

A.ย 0.707 lagging

B.ย 0.5 lagging

C.ย 0.866 lagging

D.ย none of these

Answer: **Option A**

Solution:

โ MCQ in AC Circuits Part 9 | REE Board Exam

#### Questions and Answers in AC Circuits

Following is the list of practice exam test questions in this brand new series:

**MCQ in AC Circuits**

**MCQ from Number 1 โ 50**Answer key:

**included**

**MCQ from Number 51 โ 100**Answer key:

**included**

**MCQ from Number 101 โ 150**Answer key:

**included**

**MCQ from Number 151 โ 200**Answer key:

**included**

**MCQ from Number 201 โ 250**Answer key:

**included**

**MCQ from Number 251 โ 300**Answer key:

**included**

**MCQ from Number 301 โ 350**Answer key:

**included**

**MCQ from Number 351 โ 400**Answer key:

**included**

**MCQ from Number 401 โ 450**Answer key:

**included**

**MCQ from Number 451 โ 500**Answer key:

**included**

**MCQ in AC Circuits Series**

P inoyBIX educates thousands of reviewers and students a day in preparation for their board examinations. Also provides professionals with materials for their lectures and practice exams. Help me go forward with the same spirit.

โWill you subscribe today via YOUTUBE?โ

**What You Also Get: FREE ACCESS & DOWNLOAD via GDRIVE**

## TIRED OF ADS?

- Become Premium Member and experienced fewer ads to ads-free browsing.
- Full Content Access Exclusive to Premium members
- Access to PINOYBIX FREEBIES folder
- Download Reviewers and Learning Materials Free
- Download Content: You can see download/print button at the bottom of each post.

## PINOYBIX FREEBIES FOR PREMIUM MEMBERSHIP:

- CIVIL ENGINEERING REVIEWER
- CIVIL SERVICE EXAM REVIEWER
- CRIMINOLOGY REVIEWER
- ELECTRONICS ENGINEERING REVIEWER (ECE/ECT)
- ELECTRICAL ENGINEERING & RME REVIEWER
- FIRE OFFICER EXAMINATION REVIEWER
- LET REVIEWER
- MASTER PLUMBER REVIEWER
- MECHANICAL ENGINEERING REVIEWER
- NAPOLCOM REVIEWER
- Additional upload reviewers and learning materials are also FREE

## FOR A LIMITED TIME

If you subscribe for PREMIUM today!

You will receive an additional **1 month of Premium Membership** FREE.

For **Bronze Membership** an additional **2 months of Premium Membership** FREE.

For **Silver Membership** an additional **3 months of Premium Membership** FREE.

For **Gold Membership** an additional **5 months of Premium Membership** FREE.

Join the PinoyBIX community.