Engineering Reviewer - Electrical Circuits |

**Multiple Choice Questions / Practice Test**

**Electrical Circuits**

251. A neon glow lamp used as a night light ionizes at approximately

A. 70 V

B. 80 V

C. 90 V

D. 100 V

252. What dielectric is generally employed by a variable capacitor?

A. Mica

B. Air

C. Electrolyte

D. Ceramic

253. A switch designed to have low capacitance between its terminal when open.

A. LOCAP switch

B. AntiLOCAP switch

C. Anticapacitance switch

D. Capacitance switch

254. A resistor wound with a wire doubled back on itself to reduce the inductance.

A. Bifilar resistor

B. Wire-wound resistor

C. Anti-inductive resistor

D. Bleeder resistor

255. What fusion of elements is without chemical action between them?

A. Mixture

B. Compound

C. Alloy

D. Ionization

256. In calculating maximum instantaneous power ___ voltage or current is used.

A. Peak

B. Average

C. Rms

D. Instantaneous

257. The area of capacitor plates increases two times, then its capacitance

A. Increases two times

B. Increases four times

C. Decreases two times

D. Decreases four times

258. If the inductance is decreased, the impedance of the circuit containing a resistor a capacitor and an inductor connected in series to an ac source

A. Decreases

B. Increases

C. Decreases or increases

D. Decreases, increases or remains the same

259. When the movable plates of a gang capacitor completely overlap the fixed plates, the capacitance of the capacitor is

A. Halfway between maximum and minimum

B. Maximum

C. Minimum

D. Zero

260. In a circuit, a passive element is one which

A. Supplies energy

B. Receives energy

C. Both supplies and receives energy

D. Attenuates signal

261. Rationalizing the denominator of a complex number means

A. Eliminating the j component in the denominator

B. Adding j component in the denominator

C. Eliminating the j component in the numerator

D. Adding j component in the numerator

262. When two complex conjugates are subtracted, the result is a

A. Quadrature component only

B. Complex component

C. In-phase component

D. Real component

263. A coil of inductance L has an inductive reactance of XL in an ac circuit in which the effective current is I. The coil is made from a superconducting material. The rate at which power is dissipated in the coil is

A. 0

B. (I^2)XL

C. IXL

D. I(XL^2)

264. If the capacitance of mica capacitor is 5 times the capacitance of air capacitor, then the relative permittivity of mica is

A. 2.5

B. 5

C. 10

D. 25

265. The hot resistance of an incandescent lamp is about ___ times its cold resistance.

A. 10

B. 5

C. 50

D. 100

266. When the temperature of copper wire is increased its resistance is

A. Increased

B. Decreased

C. Constant

D. Zero

267. A trimmer is a variable capacitor in which capacitance is varied by changing the

A. Number of plates

B. Dielectric

C. Distance between plates

D. Plate area

268. The reason why electrical appliances are not connected in series.

A. Greater electrical power saving

B. Power loss is minimum

C. Appliances have different current ratings

D. All of the above

269. Form its definition, the unit of electric field, ξ is the N/C and equivalent unit of ξ is the

A. V(m^2)

B. V(m)

C. V/(m^2)

D. V/m

270. Which of the following is the peakiest?

A. Square wave

B. Sinusoidal wave

C. Triangular wave

D. Rectangular wave

271. Why are inductance and capacitance not relevant in a dc circuit?

A. Because it is a simple circuit

B. Because dc circuits require only resistance as load

C. Because they do not exist in a dc circuit

D. Because frequency of dc is zero

272. When capacitors are connected in parallel, the total capacitance is

A. Greater than the largest capacitor

B. Smaller than the largest capacitor

C. Smaller than the smallest capacitor

D. Greater than the smallest capacitor

273. When current and voltage arte in phase in an ac circuit, the ___ is equal to zero.

A. Resistance

B. Reactance

C. Inductance

D. Capacitance

274. Thevenin’s theorem is what form of an equivalent circuit?

A. Current

B. Voltage

C. Both current and voltage

D. Neither current nor voltage

275. Which of the following combination of length and cross-sectional area will give a certain volume of copper the least resistance?

A. 2L and1/2 A

B. Does not matter because the volume of copper remains the same

C. L and A

D. ½ L and 2 A

276. The ratio between the reactive power and the apparent power of an ac load is called

A. Quality factor

B. Power factor

C. Power ratio

D. Reactive power

277. What is the efficiency under the conditions of maximum power transfer?

A. 50 %

B. 100 %

C. 25 %

D. 75 %

278. The charging of a capacitor through a resistance follows what law?

A. Linear law

B. Hyperbolic law

C. Inverse-square law

D. Exponential law

279. Norton’s theorem is what form of an ac equivalent circuit?

A. Voltage

B. Current

C. Both voltage and current

D. Neither voltage nor current

280. What is the total capacitance of 10 capacitors, each of 20 μF in series?

A. 200 μF

B. 2 μF

C. 100 μF

D. 0.5 μF

A. Leading

B. Lagging

C. Zero

D. Unity

282. When resistance are connected in parallel, the total resistance is

A. Less than the smallest resistance in the connection

B. Greater than the smallest resistance in the connection

C. Between the smallest and greatest resistance in the connection

D. Increasing and decreasing depending upon the supply voltage

283. The arc across a switch when it open an RL circuit is a result of the

A. Large self-induced voltage across L

B. Long time constant

C. Low resistance of the open switch

D. Surge of resistance

284. What is a rotating vector whose projection can represent either current or voltage in an ac circuit?

A. Polar diagram

B. Scalar quantity

C. Velocity

D. Phasor

285. Which factor does not affect resistance?

A. Length

B. Resistivity

C. Cross-sectional area

D. Mass

286. Which of the following capacitors are used only in dc circuits?

A. Mica

B. Ceramic

C. Mylar

D. Electrolytic

287. The maximum power transfer theorem is used in

A. Power system

B. Electronic system

C. Refrigeration

D. Air conditioning

288. In Norton’s theorem, the short circuit current is obtained by

A. Opening the load terminals

B. Shorting the load terminals

C. Opening the voltage source

D. Shorting the voltage source

289. For maximum power transfer, what is the relation between load resistance RL and internal resistance R of the voltage source?

A. RL = 2 r

B. RL = 1.5 r

C. RL = r

D. RL = 3 r

290. A capacitor of 0.5 μF charged to 220 V is connected across an uncharged 0.5 μF capacitor. What is the voltage across each capacitor?

A. 220 V

B. 150 V

C. 110 V

D. 22 V

291. When capacitors are connected in series, the total capacitance is

A. Smaller than the smallest capacitor

B. Smaller than the largest capacitor

C. Greater than any of the capacitor

D. Greater than the largest capacitor

292. What theorem is generally used in the analysis of vacuum tubes?

A. Superposition theorem

B. Millman’s theorem

C. Thevenin’s theorem

D. Norton’s theorem

293. Another term of the quality factor of the resonant circuit.

A. Figure of merit

B. Figure of demerit

C. Noise factor

D. Noise figure

294. Which of the following represents the energy stored in a capacitor?

A. (CV^2)/2

B. (2Q^2)/C

C. (C^2)/V

D. CV

295. What theorem is usually used in the analysis of transistor circuit?

A. Superposition theorem

B. Millman’s theorem

C. Thevenin’s theorem

D. Norton’s theorem

296. Which of the following capacitors has the highest cost per μF?

A. Plastic

B. Air

C. Mica

D. Electrolytic

297. Under the conditions of maximum power transfer, a voltage source is delivering a power of 15 W to the load. What is the power generated by the source?

A. 60 W

B. 30 W

C. 15 W

D. 4 W

298. Which of the following is neither a basic physical law nor deliverable from one?

A. Ohm’s law

B. Coulomb’s law

C. Kirchhoff’s first law

D. Kirchhoff’s second law

299. Another term for superconductor.

A. Generic conductor

B. Ultraconductor

C. Cryotron

D. Cryogenic conductor

300. A circuit whose parameters change with voltage or current.

A. Non-linear circuit

B. Linear circuit

C. Complex circuit

D. Passive circuit

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