Yelo ELEX 1

"A 12 mA current source has an internal resistance, RS, of 1.2 kΩ. The equivalent voltage source is"

14.4 V"

"In a parallel RC circuit, there is 100 mA through the resistive branch and 100 mA through the capacitive branch. The total rms current is"

141 mA"

"Referring to the given circuit, determine ZTH as seen by RL."

1444∠-48.5°"

"120Ω resistor must carry a maximum current of 25 mA. Its rating should be at least"

150 mW"

"If in a Y-connected ac generator, each phase voltage has a magnitude of 90 VRMS, what is the magnitude of each line voltage?"

156 V"

"The voltage across a coil when di/dt = 20 mA/us and L = 8 uH is"

160 mV"

"What is the current through R2?"

173 mA"

"A basic one-loop dc generator is rotated at 90 rev/s. How many times each second does the dc output voltage peak (reach maximum)?"

180"

"The current in a given circuit is not to exceed 24 A. Which value of fuse is best?"

24 A"

"A 330 pF capacitor and a 220 pF capacitor are each connected across a 6 V dc source. The voltage across the 330 pF capacitor is"

6 V"

"A string of five series resistors is connected across a 6 V battery. Zero voltage is measured across all resistors except R3. The voltage across R3 is"

6 V"

"The minimum resistance value for a blue, gray, red, silver resistor is"

6,120Ω"

"What is the Thevenin equivalent (VTH and RTH) for the circuit given?"

6.4 V, 422"

"The parallel combination of a 6.8 kΩ resistor and a 10 kΩ resistor is in series with the parallel combination of a 2.2 kΩ resistor and a 1 kΩ resistor. A 100 V source is connected across the circuit. The resistor(s) with the greatest voltage drop is (are)"

6.8 kΩ and 10 kΩ"

"An RC low-pass filter consists of a 120 resistor and a 0.002 F capacitor. The output is taken across the capacitor. The circuit's critical frequency is"

633 kHz"

"When a 12 V input pulse with a width equal to one time constant is applied to an RC integrator, the capacitor charges to"

7.56 V"

"What is the voltage drop across R1?"

7.82 V"

"Four 8Ω speakers are connected in parallel to the output of an audio amplifier. If the maximum voltage to the speakers is 12 V, the amplifier must be able to deliver to the speakers"

72 W"

"A switch, a 220Ω resistor, and a 60 mH inductor are in series across a 20 V battery. What is the current through the inductor two time constants after the switch is closed?"

78 mA"

"If 750 µA is flowing through 11 kΩ of resistance, what is the voltage drop across the resistor?"

8.25 V"

"Two resistors are in series: a 5.6 kΩ resistor and a 4.7 kΩ resistor. The voltage drop across the 5.6 kΩ resistor is 10 V. The voltage across the 4.7 kΩ resistor is"

8.39 V"

"A sudden increase in the total current into a parallel circuit may indicate"

an increase in source voltage"

"When the frequency of the voltage applied to a series RC circuit is increased, the phase angle"

decreases"

"Which of the following is not an electrical quantity?"

distance"

"An RC differentiator acts as a"

high-pass filter"

"When the frequency of the voltage applied to a series RL circuit is increased, the phase angle"

increases"

"When the resistor voltage in a series RL circuit becomes less than the inductor voltage, the phase angle"

increases"

"The winding resistance of a coil can be increased by"

increasing the number of turns or using thinner wire"

"A 200Ω resistor, a coil with 30Ω of reactance, and a capacitor of unknown reactance are in series across an ac source. The circuit is at resonance. Circuit impedance"

is 200"

"Six resistors are in parallel. The two lowest-value resistors are both 1.2 kΩ. The total resistance"

is less than 600Ω"

"When the current through an inductor is cut in half, the amount of energy stored in the electromagnetic field"

is quartered"

"Which of the following series combinations dissipates the most power when connected across a 120 V source?"

one 220Ω resistor"

"A wiper is the sliding contact in a"

potentiometer"

"A circuit breaker is a"

resettable protective device"

"A thermistor is a type of"

resistor"

"The ability of a material to remain magnetized after removal of the magnetizing force is known as"

retentivity"

"A two-terminal variable resistor is known as a"

rheostat"

"When the pointer of an analog ohmmeter reads close to zero, the resistor being measured is"

shorted"

"The two basic components of a Thevenin equivalent ac circuit are"

the equivalent voltage source and the equivalent series impedance"

"The inductance of an iron-core coil decreases if"

the number of turns is decreased"

"The Thevenin equivalent voltage is"

the open circuit voltage"

"The most common type of ac motor is the"

three-phase induction motor"

"The colored bands for a 4,700 ohm resistor with a ten percent tolerance are"

yellow, violet, red, silver"

"A sinusoidal voltage with a peak-to-peak value of 18 V is applied to an RC low-pass filter. If the reactance at the input frequency is zero, the output voltage is"

zero"

"In assigning the direction of branch currents

,"the directions are not critical"

"Three lights are connected in parallel across a 120 volt source. If one light burns out

,"the remaining two will glow with the same brightness as before"

"In applying the superposition theorem

,"the sources are considered one at a time with all others replaced by their internal impedance"

"The output voltage of a filter is 6 V and the input is 12 V. The voltage ratio in decibels is"

-6.02 dB"

"In a certain low-pass filter, fc = 3.5 kHz. Its passband is"

0 Hz to 3.5 kHz"

"An uncharged capacitor and a 1 k resistor are connected in series with a switch and a 6 V battery. At the instant the switch is closed, the voltage across the capacitor is"

0 V"

"The primary of a transformer is connected to a 6 V battery. The turns ratio is 1:3 and the secondary load, RL, is 100Ω. The voltage across the load is"

0 V"

"To step 110 V ac down to 20 V ac, the turns ratio must be"

0.18"

"Eight-tenths coulomb passes a point in 4 s. The current in amperes is"

0.2 A"

"Four 0.15 uF capacitors are in parallel. The total capacitance is"

0.6 uF"

"What is the coefficient of coupling for a transformer in which 4% of the total flux generated in the primary does not pass through the secondary?"

0.96"

"On which of the following voltage range settings will a voltmeter present the minimum load on a circuit?"

1,000 V"

"A 12 kΩ resistor, a 15 kΩ resistor, and a 22 kΩ resistor are in series with two 10 kΩ resistors that are in parallel. The source voltage is 75 V. Current through the 15 kΩ resistor is approximately"

1.4 mA"

"A 15Ω resistor, a 220 uH coil, and a 60 pF capacitor are in series across an ac source. What is the bandwidth of the circuit?"

10,866 Hz"

"A series resonant band-pass filter consists of a 2 mH coil, a 0.005 uF capacitor, and a 120Ω resistor. The winding resistance of the coil is 12Ω. The output voltage is taken off the resistor. Input voltage is 12 Vrms. What is the output voltage magnitude at the center frequency (f0)?"

10.9 V"

"A sawtooth wave has a period of 10 ms. Its frequency is"

100 Hz"

"What is the reluctance of a material that has a length of 0.07 m, a cross-sectional area of 0.014 m2, and permeability of 4,500 uWb/At × m?"

1111 At/Wb"

"Using the mesh current method, find the branch current, IR1, in the above figure."

115 mA"

"A sine wave of 15 kHz is changing at a faster rate than a sine wave with a frequency of"

12 kHz"

"A certain voltage divider consists of two 12 kΩ resistors in series. Which of the following load resistors will have the most effect on the output voltage?"

12 kΩ"

"In a five-branch parallel circuit, there are 12 mA of current in each branch. If one of the branches opens, the current in each of the other four branches is"

12 mA"

"In a three-phase system, the voltages are separated by"

120°"

"An RL high-pass filter consists of a 470Ω resistor and a 600 mH coil. The output is taken across the coil. The circuit's critical frequency is"

125 Hz"

"A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470Ω. The load resistance as seen by the source is"

13 Ω"

"Determine VTH for the circuit external to RL in the given figure."

13.5∠63.4° V"

"A 90Ω resistor, a coil with 30Ω of reactance, and a capacitor with 50Ω of reactance are in series across a 12 V ac source. The current through the resistor is"

130 mA"

"In a series RC circuit, 12 V(rms) is measured across the resistor and 15 V(rms) is measured across the capacitor. The rms source voltage is"

19.2 V"

"A 120 V voltage source has a source resistance, RS, of 60Ω. The equivalent current source is"

2 A"

"The power rating of a carbon-composition resistor that is to handle up to 1.2 W should be"

2 W"

"In a certain five-step R/2R ladder network, the smallest resistor value is 1 kΩ. The largest value is"

2 kΩ"

"A 12 kΩ resistor is in series with a 90 mH coil across an 8 kHz ac source. Current flow in the circuit, expressed in polar form, is I = 0.3∠0° mA. The source voltage, expressed in polar form, is"

3.84∠20.6° V"

"What is the magnetomotive force in a 75-turn coil of wire when there are 4 A of current through it?"

300 At"

"A 24Ω resistor, an inductor with a reactance of 120Ω , and a capacitor with a reactance of 120Ω are in series across a 60 V source. The circuit is at resonance. The voltage across the inductor is"

300 V"

"A certain Wheatstone bridge has the following resistor values: R1 = 10 kΩ, R2 = 720Ω , and R4 = 2.4 kΩ. The unknown resistance is"

3000Ω"

"Four resistors are connected in parallel. Fifteen mA flows through resistor R. If the second resistor is 2R, the third resistor 3R, and the fourth resistor 4R, the total current in the circuit is"

31.25 mA"

"What is the highest frequency contained in a pulse that has a rise and fall time equal to 10 microseconds?"

35 kHz"

"A sinusoidal current has an rms value of 14 mA. The peak-to-peak value is"

39.6 mA"

"A waveform has a baseline of 3 V, a duty cycle of 20%, and an amplitude of 8 V. The average voltage value is"

4 V"

"Point +4 on the complex plane is"

4 units right of the origin on the real axis"

"A 12 kΩ resistor is in series with a 0.02 uF capacitor across a 1.2 kHz ac source. If the current is expressed in polar form as I = 0.3∠0° mA, what is the source voltage expressed in polar form?"

4.11 V"

"What is the voltage drop across R2?"

4.18 V"

"In a parallel RL circuit, there are 3 A rms in the resistive branch and 3 A rms in the inductive branch. The total rms current is"

4.24 A"

"The voltage and current for the load resistor, RL, of the circuit is"

4.50 V, 4.5 mA"

"One sine wave has a positive-going zero crossing at 15° and another sine wave has a positive-going zero crossing at 55°. The phase angle between the two waveforms is"

40°"

"Find the Thevenin equivalent (VTH and RTH) between terminals A and B of the circuit given."

41.67 V, 70Ω"

"Find the Norton circuit, that is, IIN and RN, for the circuit given below."

478 mA, 12.8Ω"

"A 220Ω resistor is in series with a 2.2 uF capacitor. The time constant is"

480 us"

"Find the node voltage VA."

5.18 V"

"A 2 mH, a 3.3 mH, and a 0.2 mH inductor are connected in series. The total inductance is"

5.5 mH"

"An ammeter has an internal resistance of 50Ω. The meter movement itself can handle up to 1 mA. If 10 mA is applied to the meter, the shunt resistor, RSH1, is approximately"

5.5Ω"

"A voltage divider consists of two 100 kΩ resistors and a 12 V source. What will the output voltage be if a load resistor of 1 MΩ is connected to the output?"

5.7 V"

"For the circuit given, determine the Thevenin voltage as seen by RL."

5.74∠-16.7° V"

"A square wave has a period of 60us. The first odd harmonic is"

50 kHz"

"A 2Ω RL is connected across a voltage source, VS, of 110 V. The source's internal resistance is 24Ω. What is the output voltage across the load?"

8.5 V"

"Two inductors, L1 and L2, are in parallel. L1 has a value of 25 uH and L2 a value of 50 uH. The parallel combination is in series with L3, a 20 uH coil. The entire combination is across an ac source of 60 Vrms at 300 kHz. The total rms current is"

870 mA"

"You are measuring the current in a circuit that is operated on an 18 V battery. The ammeter reads 40 mA. Later you notice the current has dropped to 20 mA. How much has the voltage changed?"

9 V"

"Referring to the given circuit, find ZTH if R is 15 kΩ and RL is 38 kΩ."

9.38∠-51.3° kΩ"

"The impedance at the resonant frequency of a series RLC circuit with L = 20 mH, C = 0.02 uF, and RW = 90Ω"

90 Ω"

"Four amperes of current are measured through a 24Ω resistor connected across a voltage source. How much voltage does the source produce?"

96 V"

"The unit for reluctance is"

At/Wb"

"The branch current method uses"

Kirchhoff's voltage and current laws"

"In a certain three-branch parallel circuit, R1 has 12 mA through it, R2 has 15 mA through it, and R3 has 25 mA through it. After measuring a total of 27 mA, you can say that"

R3 is open"

"A capacitor and a resistor are connected in series to a sine wave generator. The frequency is set so that the capacitive reactance is equal to the resistance and, thus, an equal amount of voltage appears across each component. If the frequency is increased"

VR > VC"

"A 47Ω resistor and a capacitor with 150Ω of capacitive reactance are in series across an ac source. The impedance, expressed in rectangular form, is"

Z = 47Ω - j150Ω"

"In a series resonant band-pass filter, a lower value of Q results in"

a larger bandwidth"

"To understand how the output voltage is shaped by a differentiator, you must consider"

all of the above"

"To measure the current of the second resistor in a circuit of four resistors, an ammeter can be placed"

at any point in the circuit"

"If the frequency is halved and the resistance is doubled, the impedance of a series RL circuit"

cannot be determined without values"

"The output of an RC integrator is taken across the"

capacitor"

"Polyphase generators produce simultaneous multiple sinusoidal voltages that are separated by"

certain constant phase angles"

"Materials with lots of free electrons are called"

conductors"

"The unit of electrical charge is the"

coulomb"

"An electromagnetic field exists only when there is"

current"

"A certain series resonant circuit has a bandwidth of 2 kHz. If the existing coil is replaced with one having a higher value of Q, the bandwidth will"

decrease"

"To tune a parallel resonant circuit to a higher frequency, the capacitance should be"

decreased"

"A sine wave voltage is applied across a capacitor. If the frequency of the voltage is decreased, the current"

decreases"

"The output of a certain voltage divider is 12 V with no load. When a load is connected, the output voltage"

decreases"

"When load resistance is removed from the output of voltage divider circuit, current drawn from the source"

decreases"

"When the current through an inductor decreases, the amount of energy stored in the electromagnetic field"

decreases"

"When the frequency is decreased, the impedance of a parallel RL circuit"

decreases"

"A constant load power means a uniform conversion of"

electrical to mechanical energy"

"In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is"

four times the primary current"

"The primary winding of a power transformer should always be"

fused"

"Of the following capacitors, which one has the highest dielectric constant?"

glass"

"In order to get maximum power transfer from a capacitive source, the load must"

have an impedance that is the complex conjugate of the source impedance"

"For a given wirewound core, an increase in current through the coil"

increases the flux density"

"If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage"

increases"

"When one of three series resistors is removed from a circuit and the circuit is reconnected, the current"

increases"

"When the frequency of the source voltage decreases, the impedance of a parallel RC circuit"

increases"

"When the frequency of the voltage applied to a series RC circuit is decreased, the impedance"

increases"

"In a three-phase system, when the loads are perfectly balanced, the neutral current is"

zero"

"When the plate area of a capacitor increases

,"the capacitance increases"

"A resistor is connected across a 50 V source. What is the current in the resistor if the color code is red, orange, orange, silver?"

2.2 mA"

"A certain appliance uses 350 W. If it is allowed to run continuously for 24 days, how many kilowatt-hours of energy does it consume?"

201.6 kWh"

"A 120V lamp-dimming circuit is controlled by a rheostat and protected from excessive current by a 3A fuse. To what minimum resistance value can the rheostat be set without blowing the fuse? Lamp resistance is 20 ohms."

20Ω"

"When a 24 V input pulse with a width equal to five time constants is applied to an RC integrator, the capacitor charges to"

24 V"

"When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is"

240 V"

"Determine IN for the circuit consisting of VS, R1, R2, and R3 shown in the given circuit."

245 mA"

"If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power delivered to the secondary load is"

25 W"

"The average half-cycle value of a sine wave with a 40 V peak is"

25.48 V"

"In a series RL circuit, 12 V rms is measured across the resistor, and 14 V rms is measured across the inductor. The peak value of the source voltage is"

26.0 V"

"If the rms current through a 4.7 k resistor is 4 mA, the peak voltage drop across the resistor is"

26.6 V"

"A certain series circuit consists of a 1/8 W resistor, a 1/4 W resistor, and a 1/2 W resistor. The total resistance is 1200Ω. If each resistor is operating at its maximum power dissipation, total current flow is"

27 mA"

"Five resistors are connected in a series and there is a current of 3 A into the first resistor. The amount of current into the second resistor is"

3 A"

"The number of megaohms in 0.03 kilohms is"

3 × 10-5 MΩ"

"An RC high-pass filter consists of a 0.2 F capacitor and a 220Ω resistor. The output is taken across the resistor. The circuit's critical frequency is"

3,617 Hz"