A circuit consists of XL = j5 ohms, XC = -j5 ohms and R = 5 ohms all are connected in parallel. Find the equivalent impedance.
A. 5.5 Ω C. 4.8 Ω
B. 5.0 Ω D. 5.2 Ω
343. EE Board Exam October 1985
Given: Z1 = -j2.5 ohms; Z2 = j4 ohms; Z3 = 5 ohms; Z4 = 1 + j5 ohms. If the four impedances are connected in parallel, find the equivalent impedance in ohms.
A. 4.1 + j0.72 C. 4.2 + j0.35 B. 4.3 + j0.45 D. 4.0 + j0.97 344. EE Board Exam April 1984, April 1987
Three impedances Za = 3 + j4 ohms, Zc = 4 – j4 ohms and Zc = j3 ohms are connected in parallel. Solve for the pf of the combination.
A. 0.653 leading C. 0.503 leading B. 0.554 lagging D. 0.620 lagging 345. EE Board Exam October 1993
A pure capacitance of 530.515 x 10-6 farad and an inductance of 530.515 x 10-4 Henry are connected in parallel across an ac power source. Solve for the resultant impedance assuming that the frequency is 30 Hz.
A. 10 Ω C. zero
B. infinite D. undefined
346. REE Board Exam March 1998
A coil of a 50-ohm resistance and of 150 mH inductance is connected in parallel with a 50 μF capacitor. What is the power factor of the circuit?
A. 80% C. 70%
B. 50% D. 60%
347. EE Board Exam April 1982
Three impedances Za, Zb and Zc are connected in parallel. If at 60 Hz, Za = j8, Zb = -j2 and Zc = 5 ohms. Solve for the resultant power factor.
A. 0.471 lagging C. 0.573 lagging B. 0.471 leading D. 0.573 leading 348. REE Board Exam October 1997
A resistor of 50 ohms and an impedance of 100 + j50 ohms are connected in parallel across a 220 volts supply. What is the power factor of the load?
A. 96% C. 98%
B. 99% D. 95%
349. EE Board Exam October 1992
A capacitor of 3.18 microfarads is connected in parallel with a resistance of 2,000 ohms. The combination is further connected in series with an inductance of 795 mH and resistance of 100 ohms across a supply given by e = 400 sin wt + 80 sin (3wt + 60°). Assume w = 314 radians/sec. Determine the power dissipated.
A. 74.66 W C. 80.28 W
B. 78.05 W D. 75.66 W
350. EE Board Exam October 1992
A capacitor of 3.18 microfarads is connected in parallel with a resistance of 2,000 ohms. The combination is further connected in series with an inductance of 795 mH and resistance of 100 ohms across a supply given by e = 400 sin wt + 80 sin (3wt + 60°). Assume w = 314 radians/sec. Determine the circuit power factor.
A. 0.702 C. 0.633
B. 0.650 D. 0.612
351. EE Board Exam April 1990
A capacitor, an electric resistance heater, and impedance are connected in parallel to a 120 V, 60 Hz system. The capacitor draws 50 var, the heater draws 100 W and the impedance coil draws 269 VA at a pf 0f 0.74 lagging. Determine the system power factor.
A. 0.933 leading C. 0.916 lagging B. 0.928 lagging D. 0.911 lagging 352. REE Board Exam October 1996
A bank of capacitors is connected in parallel each rated at 10 kVAR, 380 volts. If one unit is shorted out, what would be the net capacitance of the bank?
A. 330 μF C. 220 μF
B. 440 μF D. 110 μF
353. EE Board Exam October 1992
A capacitor of 3.18 microfarads is connected in parallel with a resistance of 2,000 ohms. The combination is further connected in series with an inductance of 795 mH and resistance of 100 ohms across a supply given by e = 400 sin wt + 80 sin (3wt + 60°). Assume w = 314 radians/sec. Determine the rms value of the total current.
A. 0.40 A C. 0.56 A
B. 0.33 A D. 0.45 A
354. EE Board Exam June 1990
Three loads, units A, B and C are connected in parallel and take currents that are respectively 12, 10 and 15 A respectively. Assuming Ia to be the reference phasor. Ib leads Ia by 30° and Ic lags behind Ia by 65°, calculate the total (resultant) current.
A. 28.33 A C. 26.46 A
B. 30.21 A D. 32.10 A
355. EE Board Exam April 1992
Two single-phase motors are connected in parallel across a 120-volt, 60-cycle source of
supply. Motor A is a split-phase inductance type and motor B is a capacitor type:
Motor HP Output Efficiency pf Determine total power factor.
A. 0.886 lag C. 0.817 lag
B. 0.864 lag D. 0.825 lag 356. 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.
Determine the system power factor.
A. 0.828 lagging C. 0.802 lagging B. 0.831 lagging D. 0.884 lagging 357. EE Board Exam April 1985
A resistance of 5 ohms is connected in series with a capacitor of 442.1 μF. The combination is then connected in parallel with an inductance of 21.22 mH. Solve for the resultant current if the circuit is connected across a 120 V, 60 Hz ac source.
A. 9.44 A C. 11.29 A
B. 10.68 A D. 10.34 A
358. EE Board Exam April 1993
An inductor L1 is connected in series with a parallel combination of inductor L2 and capacitor C. The impedance of the circuit w = 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. 1.28 μF C. 2.06 μF
B. 1.67 μF D. 1.32 μF
359. EE Board Exam April 1992
A sinusoidal current source, 10 cos 1000t, is in parallel both with a 20-ohm resistor and the series combination of a 10-ohm resistor and a 10-mH inductor. Find the equation of the voltage across the 10-ohm resistor.
A. 63.25 cos (1000t – 18.43°) B. 61.32 cos (1000t – 20.34°) C. 59.36 cos (1000t – 17.45°) D. 60.12 cos (1000t – 19.38°)
360. 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 90
apart at starting,
A. 186.75 μF C. 182.43 μF
B. 174.35 μF D. 170.67 μF
361. EE Board Exam October 1990
Two impedances A and B are connected in parallel across a 120 V ac supply. The total current and the current in each impedance is adjusted to 20 A. The power drawn by A is doubled that of B and the power factor is lagging. Determine the power factor of A.
A. 0.650 lagging C. 0.841 lagging B. 0.704 lagging D. 0.677 lagging 362. REE Board Exam March 1998
A coil of 50-ohm resistance and of 150-mH inductance is connected in parallel with a 50-μF capacitor. If the source voltage is 100 sin (ωt + 30°), what is the equation of the line current?
A. 1.91 sin (ωt + 52.5°) C. 1.82 sin (ωt - 62°)
B. 1.25 sin (ωt + 75.5°) D. 1.32 sin (ωt – 75.5°)
363. 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. 12 ohms C. 16 ohms
B. 25 ohms D. 20 ohms
364. EE Board Exam April 1980
Three impedances Z1 = 1 - j4 ohms, Z2 = – j6 ohms and Z3 = 4 + j3 ohms are connected in series-parallel.
Z1 is connected in series with the parallel combination of Z2 and Z3. Determine the equivalent impedance of the combination.
A. 4.32 – j1.21 ohms C. 6.76 – j5.68 ohms
B. 2.23 – j3.32 ohms D. 5.42 – j7.21 ohms
365. 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 series with a 4-ohm capacitive reactance. The whole combination is connected across a 100-volt, 60 Hz supply. How much is the total current drawn by the circuit?
A. 22.36 A C. 23.16 A
B. 20.45 A D. 19.89 A
366. EE Board Exam April 1983
A non-inductive resistor R is connected in parallel with an inductive reactance of 10 ohms.
The combination is then connected in series with a capacitive reactance of 5 ohms. The whole combination is connected across a 100-volt, 60 Hz ac source. If R is equal to 5 ohms, solve for the voltage across the parallel combination.
A. 87.53 V C. 89.44 V
B. 88.34 V D. 91.87 V
367. EE Board Exam April 1980
Three impedances Z1 = 1 - j4 ohms, Z2 = – j6 ohms and Z3 = 4 + j3 ohms respectively are connected in series-parallel. Z1 is connected in series with the parallel combination of Z2 and Z3. If this circuit is connected across a 230 V, 60 Hz source, determine the voltage across the parallel combination of Z2 and Z3.
A. 156.3 V C. 135.7 V
B. 146.8 V D. 163.2 V
368. EE Board Exam October 1980
Given three impedances: Z1 = 10 + j0 ohms, Z2 = 3 + j4 ohms and Z3 = 8 – j6 ohms. Impedance Z2 and Z3
are connected in parallel and the combination is connected in series with impedance Z1 across a 120 V single-phase 60 Hz source. Find the total power drawn by the impedance.
A. 1008 W C. 1038 W
B. 1204 W D. 1103 W
369. EE Board Exam October 1993
If admittance Y = 0.06 – j0.08 mho, then conductance G equals
A. -0.06 C. 0.08
B. 0.06 D. -0.08
370. 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. 0.11 + j0.13 ohms C. 0.12 + j0.16 ohms
B. 0.13 + j0.11 ohms D. 0.16 + j0.12 ohms
371. REE Board Exam October 1994
A capacitor branch having a ratio of XC to R of 5 is paralleled with impedance consisting of a 4 Ω resistance and a 3 Ω inductive reactance. The power factor of the resulting circuit is 0.8 leading. Find the size of the capacitor in μF if the frequency is 60 Hz.
A. 879.9 μF C. 978.9 μF
B. 1078.9 μF D. 778.9 μF
372. 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. Tank circuit C. Storage circuit B. Store circuit D. Power circuit 373. 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. very low impedance C. lower power factor. Calculate the value of R’ and X’.
A. 8.33 Ω and 6.25 Ω C. 7.47 Ω and 7.51 Ω
B. 2.56 Ω and, 3.83 Ω D. 5.62 Ω and 9.84 Ω
375. A 25 Ω resistor, 2 mH inductor and 30 μF capacitor are connected in parallel across 100 sin (5000t +
single unknown element in the other branch has the following applied voltage and total current e = 10 cos (50t + 60°) V and i = 5.38 cos (50t – 8.23°) A. The unknown element is ____.
A. L = 0.04 H C. C = 10 μF
B. L = 0.02 H D. C = 5 μF
377. An impedance of 3 – j3 Ω is connected in parallel with 5 + j2 Ω. The voltmeter connected across 3 Ω resistance measures 45 V. Calculate the total current of the circuit.
A. 22.4 A C. 13.4 A
B. 41.3 A D. 7.91 A
378. Two impedances ZA = 4 + j6 Ω and ZB are connected in parallel. The apparent power for the impedance B is 1490 VA. Determine the total apparent power.
A. 4250 VA C. 2652 VA
B. 3290 VA D. 8031 VA
379. A feeder supplies two loads, one at 50 amperes at 50% power factor, the other 150 amperes at unity power factor. The total current supplied by the feeder is approximately ____.
A. 180 A C. 175 A
B. 200 A D. 150 A
380. A fluorescent lamp and its inductive ballast draw a 1.0 A current at 50% lagging power factor from a
120-V, 60-Hz source. What is the over-all power factor when a 26.5 μF capacitor is connected across the fixture?
What is the effective value of the total current?
A. 48.444 A C. 25.345 A
B. 34.255 A D. 84.389 A
382. Ten impedances connected in parallel draw the following individual current: 5∠0°, 5∠5°, 5∠10°, 5∠15°, 5∠20°, 5∠25°, 5∠30°, 5∠35°, 5∠40°, 5∠45°.What is the equivalent impedance that could replace the impedances if the source voltage is 100 sin 150t V?
What is the equivalent power factor of the circuit?
A. 0.924 C. 0.707
B. 0.866 D. 0.876
384. Ten impedances connected in parallel draw the following individual current: 5∠0°, 5∠5°, 5∠10°, 5∠15°, 5∠20°, 5∠25°, 5∠30°, 5∠35°, 5∠40°, 5∠45°.What element should be connected across the circuit so that the current would be in phase with the source?
A. 54 mH C. 13 mH
B. 25.4 mH D. 31 mH
385. A small single-phase, 240 V induction motor is tested in parallel with 160 Ω resistor. The motor takes 2 amperes and the total current is 3 amperes. What is the power of the whole circuit?
A. 800 W C. 220 W 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 16.5 kW and the overall power factor is to be unity?
A. 2.21∠30.1° Ω C. 5.63∠30° Ω B. 𝟑. 𝟑𝟑∠ − 𝟒𝟎. 𝟗° Ω D. 6.543∠ − 45° Ω 389. An 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 variable resistance. For what value of resistance will the power factor be 0.5?
A. 8.314 Ω C. 13.81 Ω
B. 3.318 Ω D. 1.381 Ω
390. Two impedances Z1 = 3 + j4 and Z2 = 5 – j8.66 ohms respectively are connected in parallel. If the combination is connected across a 240 V AC source, how much is the total current?
A. 44.4 A C. 40.6 A
B. 42.1 A D. 39.9 A
391. A resistance of 20 ohms and an unknown capacitance are connected 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. 42. 33 Hz C. 46.02 Hz
B. 50.12 Hz D. 44.18 Hz
392. Two parallel branches have admittances 0.3 + j0.4 and 0.2 – j0.25 S, respectively. If the current in the first branch is 10 A, determine the total current supplied to the parallel combination.
A. 10.44 A C. 15.32 A
B. 12.10 A D. 11.24 A
393. 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
395. The impedances of two parallel branches of a circuit are (10 + j10) and (10 – j10) respectively. The impedance of the parallel combination is
A. 20 + j0 C. 5 – j5
B. 10 + j0 D. 0 – j20
396. Domestic appliances are connected in parallel across ac mains because
A. it is a simple arrangement
B. operation of each appliance becomes independent of each other
C. appliances have same current ratings D. this arrangement occupies less space
397. When a parallel ac circuit contains a number of branches, then it is convenient to solve the circuit by A. phasor diagram
B. phasor algebra
C. equivalent impedance method D. none of the above
398. The power taken by the circuit shown in Fig. 13.1 is
IL
399. The active component of line current in Fig. 13.1 is
IL
400. The power factor of the circuit shown in Fig. 13.1 is
IL 401. The total line current drawn by the circuit shown in
Fig. 13.1 is
402. The power consumed in the circuit shown in Fig. 13.2 is
403. The active component of line current in Fig. 13.2 is
IL
405. The power factor of the circuit shown in Fig. 13.2 is
IL
406. The impedance of the circuit shown in Fig. 13.2 is
IL
B. 24 ohms D. none of these 407. The circuit shown in Fig. 13.2 is
IL
409. The power consumed in the circuit shown in Fig. 13.3 is
410. If the circuit shown in Fig. 13.3 is connected to 120 V dc, the current drawn by the circuit is
R1 = 4 Ω
411. The circuit shown in Fig. 13.3 is
R1 = 4 Ω
412. If the source frequency of Fig. 13.4 is low, then
R
A. coil takes a high lagging current B. coil takes a low lagging current C. capacitor takes a leading current D. circuit offers high impedance
413. If the source frequency of Fig. 13.4 is high, then
R
A. coil takes a high lagging current B. capacitor takes a high leading current C. capacitor takes a low leading current D. circuit offers high impedance
414. The circuit shown in Fig. 13.5 is
R =
415. The circuit shown in Fig. 13.5 will consume a power of
R = 100 V I1 3 Ω
Fig. 13.5
XC = XL = 4 Ω
4 Ω I2
IT
A. 1200 W C. 500 W
B. 2400 W D. none of these
416. If the admittance of a parallel ac circuit is increased, the circuit current
A. remains constant C. is increased B. is decreased D. none of these 417. The admittance of the circuit shown in Fig. 13.6 is
Fig. 13.6 R = 6 Ω
XL = 8 Ω
A. 10 S C. 0.1 S
B. 14 S D. none of these
418. The conductance of the circuit shown in Fig. 13.6 is
Fig. 13.6 R = 6 Ω
XL = 8 Ω
A. 14 S C. 0.06 S
B. 0.6 S D. none of these
419. The inductive susceptance of the circuit shown in Fig. 13.6 is
Fig. 13.6 R = 6 Ω
XL = 8 Ω
A. 8 S C. 0.08 S
B. 0.8 S D. none of these
420. The circuit shown in Fig. 13.7 is
Fig. 13.7 G = -B 0.01 S 100 V
A. resistive C. capacitive
B. inductive D. none of these 421. The power loss in the circuit shown in Fig. 13.7 is
Fig. 13.7 G = -B 0.01 S 100 V
A. 100 W C. 10 W
B. 10,000 W D. none of these
422. The conductance and susceptance components of admittance are
A. series elements B. parallel elements C. series-parallel elements D. none of the above
423. The impedance of a circuit is 10 ohms. If the inductive susceptance is 1 siemen, then inductive reactance of the circuit is
A. 10 ohms C. 100 ohms
B. 1 ohm D. none of these
424. The conductance and inductive susceptance of a circuit have the same magnitude. The power factor of the circuit is
A. 1 C. 0.707
B. 0.5 D. 0.866
425. The admittance of a circuit is (0.1 + j0.8) S. The circuit is
A. resistive C. inductive
B. capacitive D. none of these 426. In a parallel ac circuit, power loss is due to
A. conductance alone B. susceptance alone
C. both conductance and susceptance D. none of the above
427. The admittance of a parallel circuit is 0.12∠ − 30° S.
The circuit is
A. inductive C. resistive B. capacitive D. none of these 428. A circuit have an impedance of (1 – j2) ohms. The
susceptance of the circuit is
A. 0.1 S C. 0.4 S
B. 0.2 S D. none of these
429. A circuit has admittance of 0.1 S and conductance of 0.08 S. The power factor of the circuit is
A. 0.1 C. 0.08
B. 0.8 D. none of these
430. When an sinusoidal voltage is applied across R-L parallel circuit so that R = XL the phase angle will be A. 45° lagging C. 90° lagging
B. 45° leading D. 90° leading 431. In a parallel R-L circuit if IR is the current in resistor
and IL is the current in the inductor, then
A. IR lags IL by 90° C. IL leads IR by 270°
B. IR leads IL by 270° D. IL lags IR by 90°
432. The current read by the ammeter A in the ac circuit shown is the given figure is
A
3 A
1 A 5 A
A. 9 A C. 3 A
B. 5 A D. 1 A
433. In the given figure, the admittance values of the elements in siemens are YR = 0.5 + j0, YL = 0 – j1.5 and YC = 0 + j0.3 respectively. The value of I as a phasor when the voltage E across the elements is 10√0° V is
I YR YL YC
E100 V
A. 1.5 + j-.5 C. 0.5 + j1.8
B. 5 – j18 D. 5 – j12
434. For the circuit shown in the figure, how much the voltage across the inductor leads the voltage across the capacitor?
1 Ω 0.5 F
V20
L E
ω = 2 rad/s
A. 45° C. 135°
B. 90° D. 180°
435. In the circuit shown in the figure, v = cos 2t, Z2 = 1 + j. C1 is chosen so that i = cos 2t. The value of C1 is
Z2
C1
VS
I
A. 2 F C. 0.5 F
B. 1 F D. 0.25 F
436. For the given ac circuit, what is the value of I?
60 j60
-j120 I
v(t) = 120 sin ωt
A. 1 + j C. 2 - j
B. 1 + j0 D. 0 + j0
437. For the network shown in the given figure Z(0) = 3 Ω and Z(∞) = 2 Ω. The values of R1 and R2 will respectively be
R1
R2 1 F
1 Ω
Z(s) 1 F
A. 2 Ω, 1 Ω C. 3 Ω, 2 Ω
B. 1 Ω, 2 Ω D. 2 Ω, 3 Ω
438. The total impedance Z(jω) of the circuit shown is
3 Ω
-j4 Ω 17/6 Ω
3 Ω
j4 Ω
A. 6 + j0 Ω C. 0 + j8 Ω
B. 7 + j0 Ω D. 6 + j8 Ω
439. A resistance of 40 ohms and an inductive reactor of 30 ohms are joined in parallel to a 120 volts supply as shown in the figure. The power factor of the circuit is
R = 40 Ω
X = 30 Ω
120 volts I1
I2 I
A. 0.6 C. 0.8
B. 0.7 D. unity
440. In a parallel RC circuit,
A. IC lags IR by 90° C. IC leads IR by 90°
B. IR and IC are in phase D. IR leads IC by 90°
441. In a parallel RC circuit, A. VC and IR are in phase B. VC and IC are in phase C. IC and IR are in phase
D. VC and IR are 90° out of phase
442. When the frequency of the applied voltage increases in a parallel RC circuit
A. the phase angle, θT, increases B. ZEQ increases
C. ZEQ decreases D. both A and C 443. In a parallel RL circuit,
A. iL lags iR by 90°
B. iL leads iR by 90°
C. iL and iR are in phase D. iR lags iL by 90°
444. In a parallel RL circuit, A. VT and IL are in phase B. IL and IR are in phase C. VT and IR are in phase D. VT and IR are 90° out of phase
445. When the frequency of the applied voltage decreases in a parallel RL circuit
A. the phase angle, θI, becomes less negative B. ZEQ increases
C. ZEQ decreases D. both A and B
446. When the frequency of the applied voltage increases in a parallel RL circuit
A. θZ increases C. ZT increases B. ZT decreases D. both A and C 447. In an ac circuit with only parallel inductors
A. IT lags VT by 90° C. VT and IT are in
449. REE Board Exam October 2000
A series circuit consists of a 20-ohm
resistance, a 150 mH inductance and an unknown capacitance. The circuit is supplied with a voltage v
= 100 sin 377t. Find the value of capacitance at resonance.
A. 42 μF C. 34.65 μF
B. 47 μF D. 72.57 μF
450. REE Board Exam April 2001
A 5 mH pure inductance is connected in parallel with one microfarad capacitor. What frequency will the circuit be antiresonance?
A. 250 Hz C. 60 Hz
B. 2250 Hz D. 100 Hz
451. EE Board Exam April 1993
Capacitor of 30-microfarad capacitance is in series with a coil across an 8,000 cycle supply. What inductance is required for resonance?
A. 13.34 μH C. 13.19 μH
B. 10.45 μH D. 12.55 μH
452. REE Board Exam October 1998
One leg of a radio tuned circuit has a capacitance of 1 x 10-9 F. It is tuned at 200 kHz. What is the inductance of the other leg in Henry?
A. 6.33 x 10-4 C. 8.25 x 10-5 B. 20 x 10-3 D. 120 x 10-3 453. EE Board Exam April 1988
A loud speaker whose inductance is 1.15 Henry is coupled to a power tube through a condenser of 2 μF capacity. To what frequency will the combination be resonant?
A. 110 Hz C. 105 Hz
B. 108 Hz D. 100 Hz
454. REE Board Exam April 1995
What capacitance must be placed in series with an inductance of 0.05 Henry so that at 100 Hz, the impedance becomes equal to the ohmic resistance?
A. 50.7 μF C. 70.7 μF
B. 35.5 μF D. 87.0 μF
455. EE Board Exam April 1989
A coil has a resistance of 50 ohms and a reactance of 100 ohms, is shunted by a capacitor, which has practically no losses in order that the voltage across the coil be in phase with the total current supplied to the parallel combination. What is the impedance of the parallel combination under the given condition?
A. 250 ohms C. 230 ohms
B. 200 ohms D. 220 ohms
456. EE Board Exam April 1983
A non-inductive resistor R is connected in parallel with an inductive reactance of 10 ohms. The combination is then connected in series with a capacitive reactance of 5 ohms. Solve for R at which the power factor of the given circuit would be unity.
A. 10 Ω C. 13 Ω
B. 12 Ω D. 11 Ω
457. EE Board Exam October 1982
Two impedances Z1 = 15 + j20 and Z2 = 5 – jXC are connected in parallel. Solve for the values of XC so that the total current drawn by the combination will be in phase with any supply voltage V.
A. 28.54 C. 33.12
B. 30.43 D. 29.55
458. EE Board Exam April 1985
A resistance of 5 ohms is connected in series with a capacitor of 442.1 μF. The combination is then connected in parallel with an inductance of 21.22 mH. Solve for the frequency of the impressed voltage
with which the inductive reactance is equal to the capacitive reactance in magnitude.
A. 50 Hz C. 52 Hz
B. 51 Hz D. none of these
459. EE Board Exam April 1989
A coil has a resistance of 50 ohms and a reactance of 100 ohms, is shunted by a capacitor, which has practically no losses. What must be the reactance of the capacitor in order that the voltage across the coil is in phase with the total current supplied to the parallel combination?
A. 120 ohms C. 125 ohms
B. 127 ohms D. 132 ohms
460. EE Board Exam April 1982
Three impedances Za, Zb and Zc are connected in parallel. If at 60 Hz, Za = j8, Zb = -j2 and Zc = 5 ohms, Solve for the frequency at resonance.
A. 30 Hz C. 36 Hz
B. 34 Hz D. 28 Hz
461. EE Board Exam April 1981
A resistor R is connected in parallel with a 20-ohm inductive reactive. The combination is then connected in series with a 5-ohm capacitive reactance. Solve the value of R at which the power factor of the resultant impedance is unity.
A. 10.05 ohms C. 11.55 ohms
B. 9.15 ohms D. 10.73 ohms
462. EE Board Exam October 1998
A coil has a resistance of 50 ohms and a reactance of 70 ohms. A capacitor is connected in parallel to produce resonance. The source voltage is 120 V.
What is the power drawn by the circuit?
A. 162 W C. 132 W
B. 97 W D. 52 W
463. EE Board Exam April 1995
A coil is supplied with 200 volts and takes a current
A coil is supplied with 200 volts and takes a current