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| Engineering Reviewer - Electrical Circuits |
Electrical Circuits
201. The distance between the capacitor plates increases two times, then its capacitance
A. Increases two times
B. Increases four times
C. Decreases two times
D. Decreases four times
202. The ratio between the active power and the apparent power of a load in an ac circuit is called
A. Quality factor
B. Power factor
C. Power ratio
D. Power reactive
203. When the power factor of a circuit is zero,
A. Power absorbed is maximum
B. Power absorbed is minimum
C. Power absorbed is zero
D. The impedance is minimum
204. How many degrees of phase represents one full cycle?
A. 360
B. 180
C. 270
D. 90
205. Which of the following does not generally affect the value of a capacitor?
A. The dielectric material used
B. The surface area of the plates
C. The thickness of the dielectric
D. The voltage applied to the plate
206. What is the purpose of a load in an electric circuit?
A. To increase the circuit current
B. To decrease the circuit current
C. To utilize electrical energy
D. To make the circuit complete
207. The power factor of a certain circuit in which the voltage lags behind the current is 80 %. To increase the power to 100 %, it is necessary to add ___ to the circuit.
A. Inductance
B. Capacitance
C. Resistance
D. Impedance
208. Refers to the outward-curving distortion of the lines of force near the edges of two parallel metal plates that form a capacitor.
A. Skin effect
B. Night effect
C. Edge effect
D. Hall effect
209. If voltage across the plates of 2 F capacitor is increased by 4 V, then charge on the plates will
A. Decrease by 2 C
B. Increase by 2 C
C. Decrease by 4 C
D. Increase by 4 C
210. What does a capacitor store?
A. Voltage
B. Charge
C. Current
D. Power
211. The mutual inductance between two coils is ___ the reluctance of magnetic path.
A. Directly proportional to
B. Inversely proportional to
C. Independent to
D. Equal to
212. The result of rust in electrical (wire) connection is
A. Inductance
B. Conductance
C. Impedance
D. Resistance
213. Which of the following is a disadvantage of a wire-wound resistor?
A. It has reactance in radio-frequency circuits
B. It cannot handle much power
C. It draws a large amount of current
D. It cannot handle high voltage
214. The resistance of an insulator ___ when its temperature is increased.
A. Decreases
B. Remains the same
C. Increases
D. Varies
215. The wavelength of an alternating waveform depends upon the ___ of the variation.
A. Period
B. Number
C. Frequency
D. Amplitude
216. Delta to wye or wye to delta transformation technique is applied to a ___ network.
A. One-terminal
B. Two-terminal
C. Three-terminal
D. Complex
217. For greater accuracy, the value of phase angle θ should be determined from
A. Cos θ
B. Tan θ
C. Sin θ
D. Sec θ
218. Inductive reactance applies only to sine waves because it
A. Increases with lower frequencies
B. Increases with lower inductance
C. Depends on the factor 2 π
D. Decreases with higher frequencies
219. What increases the resistance of wire at high frequencies?
A. Temperature
B. Voltage
C. Skin effect
D. Insulation
220. An inductor carries 2 A dc. If its inductance is 100 μH, then what is its inductive reactance?
A. Zero
B. 1.3 kΩ
C. 628 Ω
D. -628 Ω
221. Barium-strontium titanite dielectric material is also called
A. Ceramic
B. Polyster
C. Electrolytic
D. Bakelite
222. In the 5-band method of capacitor color coding, the first band indicates
A. Temperature coefficient
B. Tolerance
C. 1st digit
D. Capacitance value
223. What is the most convenient way of achieving large capacitance?
A. By using multiplate construction
B. By using air as dielectric
C. By decreasing distance between plates
D. By using dielectric of low permittivity
224. A linear circuit is one whose parameters
A. Change with change in voltage
B. Change with change in current
C. Do not change with voltage and current
D. Change with change in voltage and current
225. For a linear circuit, ___ voltage or current is used to calculate average power.
A. Rms
B. Peak
C. Average
D. Instantaneous
226. When two coils of identical reactance are in parallel without mutual inductance, the reactance of the combination is ___ the reactance of each coil.
A. One half
B. Twice
C. Four times
D. One fourth
227. Which of the following is also known as anti-resonant circuit?
A. Parallel resonant circuit
B. Series resonant circuit
C. Tuned circuit
D. Tank circuit
228. In a complex number 5 + 10i, 10 is called ___ part.
A. Imaginary
B. Real
C. Conjugate
D. Integer
229. The presence of an electric current is made known by
A. Electric shock
B. Effects produced
C. Magnetic shock
D. Flashing
230. The reciprocal of a complex number is
A. A complex number
B. A real number
C. An imaginary number
D. A whole number
231. Which of the following has negative temperature coefficient?
A. Carbon
B. Nickel
C. Brass
D. Constantan
232. Which of the following is a common material used in wire-wound resistors?
A. Manganin
B. Carbon
C. Bronze
D. German silver wire
233. If one resistance in a series connection is open, then
A. The current is zero in all the other resistances
B. The current is maximum in all the other resistances
C. The voltage is zero across the open resistance
D. The voltage is infinite across the open resistance
234. What determines the magnitude of electric current?
A. The rate at which electrons are produced
B. The type of material used
C. The current carrying capacity of the circuit
D. The rate at which electrons pass a given point
235. For a carbon composition resistor, typical resistance values range from
A. 2.7 Ω to 22 MΩ
B. 1000 Ω to 10000 Ω
C. 10 Ω to 10 MΩ
D. 2.7 Ω to 2.7 GΩ
236. A lead conductor has a resistance of 25 Ω at 0 ˚C. Determine its resistance at -30 ˚C
A. 22 Ω
B. 24 Ω
C. 12 Ω
D. 11 Ω
237. An impedance given by 90∠-45˚ is a/an ___ impedance.
A. Inductive
B. Conductive
C. Resistive
D. Capacitive
238. If a coil has a Q of 10, it means that
A. The energy stored in the magnetic field of the coil is 10 times the energy wasted in its resistance
B. The energy wasted in its resistance is 10 times the energy stored in the magnetic field of the coil
C. It is a low Q coil
D. It is a high Q coil
239. What is the rms value of a square wave?
A. Equals its peak value
B. Equals its peak-to-peak value
C. Peak divided by square root of two
D. Peak divided by pi
240. The rms value of a triangular or sawtooth waveform is ___ times its peak value.
A. 0.577
B. 0.500
C. 0.25
D. 0.707
241. In a multiple capacitor, the plate area is
A. Increased
B. The same
C. Decreased
D. Variable
242. What is the time constant for L of 240 mH in series with R of 20 Ω?
A. 12 ms
B. 4.8 s
C. 83.3 s
D. 12 s
243. In an ac circuit, the power dissipated as heat depends on
A. Impedance
B. Capacitive reactance
C. Resistance
D. Inductive reactance
244. Which of the following dielectric materials makes the lowest-capacitance capacitor?
A. Paper
B. Mica
C. Air
D. Electrolyte
245. In adding or subtracting phasor quantities, ___ form is the most convenient.
A. Polar
B. Rectangular
C. Trigonometric
D. Exponential
246. In dividing or multiplying phasor quantities, ___ form is used.
A. Polar
B. Rectangular
C. Trigonometric
D. Exponential
247. The power factor of a circuit is equal to
A. RZ
B. XC/Z
C. XL/Z
D. R/Z
248. The capacitance of a capacitor is ___ relative permittivity.
A. Directly proportional to
B. Inversely proportional to
C. Equal to
D. Inversely proportional to the square of
249. If a multiplate capacitor has 10 plates, each of area 10 cm2, then
A. 10 capacitors will be in parallel
B. 10 capacitors will be in series
C. 9 capacitors will be in parallel
D. 9 capacitors will be in series
250. Of the equivalent combination of units, which one is not equal to watt?
A. (Ω^2)/V
B. AV
C. (A^2)Ω
D. J/s
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