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| Engineering Reviewer - Electrical Circuits |
Electrical Circuits
151. Metal tin becomes superconductor at approximately
A. 6 K
B. 3.7 K
C. 5 K
D. 4.7 K
152. In a complex resistance-reactance plane, XL is represented
A. By an axis opposite the R axis
B. By an axis perpendicular to the XC axis
C. By an axis opposite the XC axis
D. By an axis parallel to the R axis
153. When the net reactance in a series coil-capacitor circuit is zero at frequency f, the nature of its reactance of frequency 2f is
A. Inductive
B. Capacitive
C. Resistive
D. Infinite
154. Which of the following is a way of decreasing mutual inductance?
A. Moving the coils closer
B. Moving the coils apart
C. Decreasing the number of turns of either coil
D. Increasing the number of turns of either coil
155. The charging of a capacitor through a resistance obeys
A. Exponential law
B. Logarithmic law
C. Linear law
D. Square law
156. The Q-factor of a parallel resonant circuit is also known as
A. Voltage magnification factor
B. Current magnification factor
C. Gain magnification factor
D. Resonance magnification factor
157. What is the specific resistance of a pure silicon?
A. 55 Ω-mm
B. 55 Ω-m
C. 55 Ω-cm
D. 55 kΩ-m
158. A capacitance of 0.05 μF equals
A. 0.05 x 10^6 F
B. 0.05 x 10^-6 F
C. 0.05 x 10^-12 F
D. 0.05 x 10^12 F
159. A 5 μF capacitor charge to 5V has a stored charge equal to
A. 1 μc
B. 5 μc
C. 25 μC
D. 200 μc
160. The factor 0.707 for converting peak to rms applies only to
A. Square waves
B. Triangle waves
C. Sawtooth waves
D. Sine waves
161. When two in-phase sine waves that have identical frequency and amplitude are added together, then the result is a sine wave with ___ the amplitude of either.
A. Half
B. Twice
C. Four times
D. One-fourth
162. Liquids that are good conductors because of ionization are called
A. Electrolytic
B. Bases
C. Acid
D. Electrolytes
163. Tungsten filament of bulbs has a hot resistance higher than its cold resistance due to its temperature coefficient which is
A. Positive
B. Negative
C. Zero
D. Infinite
164. A term used to express the amount of electrical energy stored in electrostatic field.
A. Joules
B. Coulombs
C. Watts
D. Electron-volt
165. With double the number of turns by the same length and area, the inductance is
A. The same
B. Doubled
C. Quartered
D. Quadrupled
166. The temperature coefficient of resistance of electrolytes is
A. Negative
B. Positive
C. Zero
D. Infinite
167. What refers to the lowest voltage across any insulator that can cause current flow?
A. Conduction voltage
B. Critical voltage
C. Breakdown voltage
D. Voltage capacity
168. Capacitance increase with
A. Larger plate area and less distance between plates
B. Larger plate area and greater distance between plates
C. Smaller plate area and less distance between plates
D. Higher values of applied voltage
169. What is the resonant frequency of a circuit when L of 3 microhenrys and C of 40 picofarads are in series?
A. 14.5 kHz
B. 145 MHz
C. 14.5 MHz
D. 145 kHz
170. For a triangular and sawtooth waveform the rms voltage or current equals
A. 0.707 times peak value
B. 0.577 times peak value
C. 0.577 times average value
D. 0.707 times rms value
171. If two resistances of 9 Ω and 6 Ω are connected in parallel, the total resistance is
A. 54 Ω
B. 0.3 Ω
C. 15 Ω
D. 3.6 Ω
172. Refers specifically to steady state values of quantities in ac circuits which are complex numbers.
A. Domain
B. Scalar quantity
C. Vector quantity
D. Phasor quantity
173. A capacitor is used to
A. Block dc current
B. Pass dc current
C. Open voltage source
D. Short the voltage source
174. The usual load of a dc circuit is a/an
A. Resistor
B. Capacitor
C. Inductor
D. Both inductor and capacitor
175. The second strip of an electronic resistor color-code represents
A. The multiplier
B. The second digit of the value
C. The temperature
D. The tolerance
176. Which of the following is a preferred resistor value?
A. 520
B. 47
C. 43,000
D. 54,321
177. A three-by-three, series-parallel matrix of resistors, all having the same ohmic value, would have a net resistance of
A. One-third the value of a single resistor
B. Three times the value of a single resistor
C. The same value as a single resistor
D. Nine times the value of a single resistor
178. In an ac wave, 30 degrees of phase is ___ of a cycle.
A. ½
B. 1/12
C. 1/3
D. 1/30
179. What is the value of a carbon composition resistor with the following color code: Brown, white, orange, red
A. 190 Ω; 10 %
B. 19 kΩ; 2 %
C. 19 kΩ; 20 %
D. 1.9 kΩ; 2 %
180. The electric field strength between capacitor plates has a unit of
A. Volts per meter
B. Volts per mil
C. Amperes per meter
D. Amperes per mil
181. For multi-plate capacitor, capacitance is proportional to
A. Number of plates less one(n – 1)
B. Number of plates plus one(n + 1)
C. Number of plates less two(n - 2)
D. Number of plates (n)
182. A capacitor consists of two
A. Conductors only
B. Dielectric only
C. Conductors separated by a dielectric
D. Dielectric separated by a conductor
183. How many coulombs are delivered by a storage battery in 25 hours if it is supplying current at the rate of 3 A?
A. 2.592 x 10^5 C
B. 2.592 x 10^3 C
C. 2.592 x 10^8 C
D. 2.592 x 10^12 C
184. When frequency of an ac wave decreases, the value of XL in a coil
A. Approaches zero
B. Gets larger positively
C. Gets larger negatively
D. Stays constant
185. The temperature-resistance coefficient of pure gold is
A. 0.0034
B. 0.0037
C. 0.0038
D. 0.0039
186. The capacitor opposes any change in voltage across it by
A. Passing a voltage proportional to the rate of change of current
B. Acting as a short circuit at time equal to zero
C. Passing a current proportional to the rate of change of voltage
D. Acting as a short circuit at time equal to infinity
187. What is the most common non-sinusoidal waveform?
A. Square wave
B. Triangular wave
C. Trapezoidal wave
D. Sawtooth wave
188. Which of the following capacitors is suitable for dc filter circuits?
A. Mica
B. Ceramic
C. Paper
D. Electrolytic
189. A series RL circuit has R of 10 Ω and XL of 5 Ω, its impedance in rectangular form is given by
A. 10 + j 5 Ω
B. 10 + j 10 Ω
C. 10 – j 5 Ω
D. 10 – j 10 Ω
190. What is the reciprocal of capacitance?
A. Reluctance
B. Susceptance
C. Elastance
D. Conductance
191. If the output resistance of a voltage source is 4 Ω, it internal resistance should be
A. 4 Ω
B. 8 Ω
C. 2 Ω
D. Infinite
192. The curve between current and frequency is termed as
A. Voltage curve
B. Gain curve
C. Power curve
D. Resonance curve
193. What is the total effective capacitance of two 0.25 μF capacitors connected in series?
A. 0.125 μF
B. 1.25 μF
C. 0.50 μF
D. 2.5 if
194. What can be used to estimate resonant frequency and to find reactance at any frequency for any value of capacitor or inductor?
A. Smith chart
B. Reactance chart
C. Impedance chart
D. Resonance chart
195. For a parallel AC circuit, ___ is used as a reference phasor.
A. Voltage
B. Power
C. Current
D. Resistance
196. For a series AC circuit, ___ is not used as a reference phasor.
A. Voltage
B. Impedance
C. Current
D. Conductance
197. If a certain circuit has a current that is lagging the voltage by 45˚, then it displays
A. Pure inductive reactance
B. Resistance and capacitance reactance
C. Resistance and inductive reactance
D. Pure capacitive reactance
198. What maximum voltage can be applied across the capacitor for very short period of time?
A. Working voltage
B. Surge voltage
C. Stray voltage
D. Peak voltage
199. What is expected when two 20 kΩ, 1 watt resistor in parallel are use instead of one 10 kΩ, 1 watt?
A. Provides higher current
B. Provides less power
C. Provides more power
D. Provides wider tolerance
200. Which of the following materials has the lowest dielectric strength?
A. Glass
B. Paper
C. Mica
D. Teflon
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