Test 2 Flashcards by cy .

The total resistance of a two similar wire conductors connected in parallel is ________.

A. resistance of one wire multiplied by 4
B. same resistance of one wire
C. one half the resistance of one wire
D. double the resistance of one wire

C. one half the resistance of one wire

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What is the value of a resistor with colors from left: Orange, Blue, Gold, and Silver?

A. 34 ohms ± 10%
B. 3.6 ohms ± 10%
C. 3.4 ohms ± 10%
D. 36 ohms ± 10%

B. 3.6 ohms ± 10%

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Determine the value of a resistor with colors from left to right; Brown, Green, Gold, and Silver.

A. 1.5 ohms ± 10%
B. 15 ohms ± 10%
C. 1.5 ohms ± 20%
D. 15 ohms ± 20%

A. 1.5 ohms ± 10%

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Resistors with high value usually have lower wattage ratings because of _________.

A. varying current
B. lower current
C. bigger size
D. high current

B. lower current

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Smaller resistors usually have ________ resistance value.

A. small
B. high
C. low
D. very small

B. high

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When resistors are connected in series, what happens?

A. The effective resistance is decreased
B. Nothing
C. The tolerance is decreased
D. The effective resistance is increased

D. The effective resistance is increased

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A 33 kilo ohms resistor is connected in series with a parallel combination made up of a 56 kilo ohm resistor and a 7.8 kilo ohm resistor. What is the total combined resistance of these three resistors?

A. 63769 ohms
B. 49069 ohms
C. 95800 ohms
D. 39067 ohms

D. 39067 ohms

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If you need a 1.25 kΩ resistance and you only have resistors of 5 kΩ, how many of these available resistors you should connect in parallel to get a 1.25 kΩ value?

A. 2
B. 3
C. 4
D. 5

C. 4

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Insulating elements or materials has a capability of

A. allowing electric current to flow
B. supporting charge flow
C. preventing short circuit between conducting wires
D. making electrical circuits to be completed

C. preventing short circuit between conducting wires

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_________ is used to store electrical energy in an electrostatic field?

A. A transformer
B. A battery
C. A capacitor
D. An inductor

C. A capacitor

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What factors determine the capacitance of a capacitor?

A. Area of the plates, amount of charge on the plates and the dielectric constant of the material between the plates
B. Area of the plates, voltage on the plates and the distance between the plates
C. Area of the plates, distance between the plates, and the dielectric constant of the material between the plates
D. Area of the plates, voltage on the plates and dielectric constant of the material between the plates

C. Area of the plates, distance between the plates, and the dielectric constant of the material between the plates

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Factors that determine the capacitance of a capacitor.

A. area of the plate; directly proportional
B. distance between plate; inversely proportional
C. dielectric constant; directly proportional
D. all of these

D. all of these

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An electronic/electrical component/device used to store electrical energy.

A. Capacitor
B. Inductor
C. Resistor
D. lightning arrester

A. Capacitor

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Which of the following describes the action of a capacitor?

A. Converts ac into dc
B. Stores electrical energy
C. Opposes change in current flow
D. Creates a dc resistance

B. Stores electrical energy

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A parallel plate capacitor has the following values: k=81; d=0.025 inches; A=6 square inches. What is the capacitance of the capacitor?

A. 4.372 picofarad
B. 43.72 picofarad
C. 4372 picofarad
D. 437.2 picofarad

C. 4372 picofarad

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Five picofarad is equivalent to ________.

A. 5 x 10 to the -12th
B. 50 x 10 to the -12th
C. 5 x 10 to the -10th
D. 500 x 10 to the -10th

A. 5 x 10 to the -12th

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If two micro-farad capacitors are connected in series, what will be the total effective capacitance?

A. 0.125 microfarad
B. 0.0624 microfarad
C. 2.5 microfarad
D. 0.50 microfarad

A. 0.125 microfarad

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A 20 μF capacitor is charged by a 12-V battery. What is the stored energy at the capacitor?

A. 2.88 x 10-3 J
B. 1.07 x 10-3 J
C. 1.44 x 10-3 J
D. 2.88 x 10-2 J

C. 1.44 x 10-3 J

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Which of the following characterizes inductance?

A. Tends to oppose dc
B. Tends to oppose changes in voltage
C. Tends to oppose changes in current
D. Opposes all frequencies equally

C. Tends to oppose changes in current

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A coil of wire wound, with or without a magnetic core designed to have a higher self-inductance than a straight wire.

A. Inductor
B. Solenoid
C. Toroid
D. Inductive relay

A. Inductor

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With the same voltage applied, which of the following allows more current?

A. 25 ohms
B. 250 ohms
C. 0.25 ohms
D. 2.5 ohms

C. 0.25 ohms

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In electrical circuits, current is known as the flow of charged carriers, such as electrons. When can this happen?

A. when an electrical force (called emf) is applied
B. when material used allows electrons to flow
C. when there is circuit continuity
D. all of the above

D. all of the above

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What utilizes electrical energy in electrical circuits?

A. supply emf
B. load
C. the conducting wires
D. all of the above

B. load

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An electronic device draws 300 watts from its 24-volt power source. Find effective resistance.

A. 1.92 ohms
B. 19.20 ohms
C. 1.25 ohms
D. 12.50 ohms

A. 1.92 ohms

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A 50Ω resistor is connected in series with a 150C resistor and to a supply voltage of 20V. What is the current through the 50Ω resistor? A. 0.01 A B. 0.1 A C. 1.0 A D. 10 A

B. 0.1 A

Two resistors, 10Ω and 100Ω are connected in parallel, approximately, aht is the total resistance? A. 10Ω B. 50Ω C. 90Ω D. 100Ω

A. 10Ω

A shunt resistor is used to limit the load current to 0.5 A, if the load resistance is 100Ω and the original current is 1amp, what should be the value of the shunt resistance? A. 25Ω B. 50Ω C. 75Ω D. 100Ω

D. 100Ω

How many 1kΩ resistors to be connected in parallel are needed in order to get 100Ω? A. 2 B. 5 C. 10 D. 20

C. 10

Two resistors, R1=100Ω and R2=200Ω are connected in series, if the voltage across R2 is 20V, what is the voltage across R1? A. 5 V B. 10 V C. 15 V D. 20 V

B. 10 V

Two resistors, R1=100Ω and R2=200Ω are connected in parallel. If the current through R1 is 1 A, what would be the current on R2? A. 0.125 A B. 0.25 A C. 0.35 A D. 0.50 A

D. 0.50 A

A 6A current source drives a load consisting a parallel combination of R1 = 50Ω and R2 = 25Ω. Determine the current I1 through R1. A. 1 amp B. 2 amps C. 3 amps D. 4 amps

B. 2 amps

A constant voltage source Vs = 60 is delivering a power to a series combination of R1 = 100Ω, R2 = 200Ω and R3 = 300Ω. Calculate the voltage drop across R2. A. 10 V B. 20 V C. 30 V D. 40 V

B. 20 V

If 12 V are applied to a circuit that consumes 78 W, what is the current flow through the circuit? A. 6.5 A B. 936 A C. 0.15 A D. 9.36 A

A. 6.5 A

Find the current that flows through the filament of a 400 watts flat iron connected to a 220 Volt power line. A. 50 mA B. 5 A C. 5 mA D. 500 mA

D. 500 mA

An electrical device has a resistance of 10Ω and is supplied with a 5 ampere constant current source. If the deice is rated 100 Vdc, determine its power consumed. A. 250 W B. 450 W C. 750 W D. 1000 W

A. 250 W

The power dissipated by a 10 Ω load resistor with a current rating of 5 amperes is _________ if supplied with a 20 volt dc potential. A. 40 W B. 80 W C. 160W D. 250 W

A. 40 W

The power in a circuit consisting of two equal resistors in series is known to be 10 watts. If the two resistors are connected in parallel, what would be the circuit power dissipation? A. 2.5 watts B. 5 watts C. 20 watts D. 40 watts

D. 40 watts

How many nodes are needed to completely analyze a circuit according to kirchhoffs current law? A. two B. all nodes in the circuit C. one less than the total number of nodes in the circuit D. one

C. one less than the total number of nodes in the circuit

Loop currents should be assumed to flow in which direction? A. Straight B. Either C or D arbitrarily selected C. Counter-clockwise D. Clockwise

B. Either C or D arbitrarily selected

What theorem we should use in solving electrical circuits with several voltage sources? A. superposition B. Norton C. Thevenin D. Kirchhoff

A. superposition

In a mesh, the algebraic sum of all voltages and voltage drops is equal to zero. A. superposition theorem B. Nortons law C. Kirchhoffs first law D. Kirchhoffs second law

D. Kirchhoffs second law

The sum of all currents entering a junction is equal to the sum of currents leaving away from that junction. A. Kirchhoffs first law B. Kirchhoffs second law C. Nortons theorem D. Thevenins theorem

A. Kirchhoffs first law

Theorem used to simplify complex circuits wherein, the simplified circuit contains an equivalent open circuit resistance and open circuit voltage. A. Nortons B. Thevenins C. Maxwells D. Kirchhoffs

B. Thevenins

Considered as the reverse of Thevenins theorem. A. Maxwell B. Superposition C. Kirchhoff D. Nortons

D. Nortons

A certain Thevenin equivalent circuit has parameters RTH = 10 Ω and VTH = 20 V. If this is converted to Norton’s equivalent circuit, RN and IN would be A. 10Ω and 2A B. 10Ω and 4A C. 0.10 and 2A D. 0.10 and 4A

A. 10Ω and 2A

RN and IN of a Norton’s equivalent circuit are known to be 100Ω and 10A, respectively. If a 400Ω load is connected, it will have a load current of A. 1 A B. 2 A C. 3 A D. 4 A

B. 2 A

A chosen closed path of current flow in a network. In making this current path there should be no node nor elements that are passed more than once. A. node B. junction C. mesh D. loop

C. mesh

A set of circuit elements that forms a closed path in a network over which signal can circulate. A. node B. junction C. mesh D. loop

D. loop

In a network, what do we call a reference point chosen such that more branches in a circuit met. A. node B. junction C. ground D. mesh

A. node

A common connection between circuit elements or conductors from different branches. A. node B. junction C. ground D. mesh

B. junction

The return point in a circuit, where all voltage measurements are referred. A. node B. junction C. ground D. loop

C. ground

Mesh analysis is best used together with what circuit law? A. KVL B. KCL C. VDT D. CDT

A. KVL

Nodal analysis is best used together with A. KVL B. KCL C. VDT D. CDT

B. KCL

Three 100Ω resistors are connected in a tee-form (T) network and is set up between a 100 V supply and a load resistor RL. If maximum power transfer is desired, what should be the resistance of the load resistor RL? A. 50 Ω B. 75 Ω C. 125 Ω D. 150 Ω

D. 150 Ω

Theorem used in simplifying circuit analysis by considering the effect of supply voltages one at a time. A. Thevenin’s theorem B. Norton’s theorem C. Superposition D. KVL

C. Superposition

Three resistors, R1 = 60 Ω, R2 = 80 Ω and R3 = 100 are connected in delta. If the network is to be transformed into star, what would be the value of the resistor opposite of R2? A. 25.0 Ω B. 33.3 Ω C. 45.0 Ω D. 56.7 Ω

A. 25.0 Ω

The description of two sine waves that are in step with each other going through their maximum and minimum points at the same time and in the same direction A. phased sine wave B. sine waves in phase C. sine wave in coordination D. stepped sine waves

B. sine waves in phase

Most ac-supplies are in the form of A. sine-wave B. square-wave C. triangular-wave D. rectangular-wave

A. sine-wave

Advantage(s) of ac over dc A. economically produced B. transmission of ac is more efficient C. ac voltages can be easily changed D. all of the above

D. all of the above

An ac-voltage has an equation v = 240 sin120πt, its frequency is A. 60 Hz B. 90 Hz C. 120 Hz D. 240 Hz

A. 60 Hz

When can an ac-voltage, v = 120sin120πt reach its first peak? A. 4.167 μs B. 8.334 μs C. 4.167 ms D. 8.334 ms

C. 4.167 ms

Calculate the period of an alternating current having an equation of I = 20sin120πt. A. 4.167 ms B. 8.33 ms C. 16.67 ms D. 33.33 ms

C. 16.67 ms

The time taken by an alternating voltage, v = 100sin240πt to reach 50V for the first time A. 358 μs B. 695 μs C. 358 ms D. 695 ms

D. 695 ms

An alternating voltage of sine-wave form has a maximum voltage of 311V. What is its value at 225°? A. 110 V B. 220 V C. -220 V D. -110 V

C. -220 V

If an alternating voltage has a magnitude of 10 V at 30°, what is its maximum voltage? A. 20 V B. 30 V C. 40 V D. 50 V

A. 20 V

What is the frequency of an alternating current, if it reaches 90° within 4.167 ms? A. 20 Hz B. 30 Hz C. 50 HZ D. 60 Hz

D. 60 Hz

At what angle does an alternating voltage of cosine-waveform reaches its negative peak? A. 45° B. 90° C. 135° D. 180°

D. 180°

When comparing rms voltages and average voltages, which of the following statement is true, assuming sine waves? A. Either the rms voltage or the average voltage might be larger B. The rms voltage is always greater than the average voltage C. There will always be a very large difference between the rms voltage and the average voltage D. The average voltage is always greater than the rms voltage

B. The rms voltage is always greater than the average voltage

What is the average voltage of an alternating voltage, v = 100sin120πt? A. 31.8 V B. 63.6 V C. 70.71 V D. 0 (zero) V

D. 0 (zero) V

Determine the effective voltage of v = 100sin120πt. A. 31.80 V B. 35.35 V C. 70.71 V D. 90.00 V

D. 90.00 V

What do you mean by root-mean-squared (rms) value? A. it is the average value B. it is the effective value C. it is the value that causes the same heating effect as a dc-voltage D. B or C

D. B or C

The power dissipated across the resistance in an AC circuit A. real power B. reactive power C. apparent power D. true power

D. true power

In AC circuit, resistors will dissipate what power? A. reactive B. passive C. inductive D. true

D. true

In an ac-circuit, if the voltage and current are in phase, the circuit is A. resistive B. reactive C. capacitive D. inductive

A. resistive

If the current in an ac-circuit leads the voltage by 90°, the circuit is A. resistive B. capacitive C. inductive D. purely inductive

B. capacitive

In a purely inductive circuit the current A. leads the voltage by 45° B. leads the voltage by 90° C. lags the voltage by 90° D. lags the voltage by 45°

C. lags the voltage by 90°

If the current and voltage in an ac-circuit has a phase difference, it would mean the load is A. resistive B. capacitive C. inductive D. reactive

D. reactive

A resistive and a capacitive load of equal magnitude is connected in series, determine the phase difference between the voltage and the current. A. current leads the voltage by 45° B. current lags the voltage by 45° C. current leads the voltage by 90° D. current lags the voltage by 90°

A. current leads the voltage by 45°

The reactance of a 25 mH coil at 500 Hz is which of the following? A. 785 ohms B. 785,000 ohms C. 13 ohms D. 0.0013 ohms

A. 785 ohms

The impedance in the study of electronics is represented by resistance and ________. A. inductance and capacitance B. inductance C. reactance D. capacitance

C. reactance

A series circuit consists of an 80 mH inductor and a 150μF capacitor. Calculate the total reactance if it is connected to a 220-volt 60-cycle source. A. 12.5 Ω inductive B. 12.5 Ω capacitive C. 47.8 Ω inductive D. 47.8 Ω capacitive

A. 12.5 Ω inductive

82. Ignoring any inductive effects, what is the impedance of RC series capacitor made up of a 56 kilo ohms resistor and a 0.33 μF capacitor at a signal frequency of 450 Hz? A. 66,730 ohms B. 57,019 ohms C. 45,270 ohms D. 10,730 ohms

B. 57,019 ohms

A 220-volt, 60-Hz source is driving a series RL circuit. Determine the current in the circuit if R = 100 Ω and XL = 100 Ω. A. 1.10 A (lagging) B. 1.55 A (lagging) C. 2.20 A (lagging) D. 4.40 A (lagging)

B. 1.55 A (lagging)

How many electrical degrees a current will lead the voltage in a series RC load with R = 100 Ω and XC = 50 Ω? A. 13.28° B. 26.56° C. 31.72° D. 63.44°

B. 26.56°

What will be the current equation in a series RC network if supplied with v = Vmsin120πt source. The circuit has a power factor pf = 0.5? A. i = Imaxsin(120πt + 60) B. i = Imaxsin(120πt - 60) C. i = Imaxsin(120πt + 30) D. i = Imaxsin(120πt - 30)

A. i = Imaxsin(120πt + 60)

The power factor (pf) of a series LC circuit is A. 0 B. 0.5 C. 0.75 D. 1.0

A. 0

What is the power factor (pf) of a series RL circuit having R = 50Ω and XL = 20Ω? A. 0.63 B. 0.71 C. 0.81 D. 0.93

D. 0.93

A 200Ω resistor if connected in series with a capacitive reactance of 100 will give a total circuit impedance of A. 173.2 Ω B. 223.6 Ω C. 250.6 Ω D. 300.0 Ω

B. 223.6 Ω

What will happen when the power factor of a circuit is increased? A. reactive power increases B. active power increases C. both active and reactive powers increases D. both active and reactive powers decreases

B. active power increases

A series RL network is supplied with a 200-volt, 60-cycle source. If the voltage across the resistor R is 100 V, what is the voltage across the inductor L? A. 0 V B. 100 V C. 173.2 V D. 200 V

C. 173.2 V

A 6-Ω resistor is connected in series with a capacitive reactance of 8 Ω. If the supply voltage is 200 V, what is the power consumed by the circuit? A. 2400 W B. 4000 W C. 5000 W D. 6666.67 W

A. 2400 W

A 6-Ω resistor is connected in series with a capacitive reactance of 8 Ω. If the supply voltage is 200 V, what is the circuit current magnitude? A. 14.28 A B. 20 A C. 25 A D. 33.33 A

B. 20 A

A 6-Ω resistor is connected in series with a capacitive reactance of 8 Ω. If the supply voltage is 200 V, what is the apparent power of the circuit? A. 1200 W B. 2400 W C. 3200 W D. 4000 W

D. 4000 W

The apparent power of a series RC network is given to be 4000 W. If R = 6 Ω, and XC = 8 Ω, calculate the true power of the network. A. 1200 W B. 2400 W C. 3200 W D. 4000 W

B. 2400 W

A series RC circuit has an apparent power of 4000 W. If R = 6Ω, and XC = 8Ω, determine the reactive power. A. 1200 W B. 2400 W C. 3200 W D. 4000 W

C. 3200 W

A network has a true power and a reactive power of 2400 W and 3200 W respectively. What is its apparent power? A. 800 W B. 1600 W C. 4000 W D. 5600 W

C. 4000 W

What is the total impedance of a series circuit consisting of R = 6Ω, XC = 8Ω, and XL = 16Ω? A. 10 Ω B. 14 Ω C. 24.73 Ω D. 30 Ω

A. 10 Ω

What is the significance of connecting loads in parallel? A. it makes power consumption less B. it provides greater efficiency C. it increases the safety factor D. it allows independent operations of loads

D. it allows independent operations of loads

A parallel RL circuit with R = 60Ω, and XL = 40Ω has a total impedance of A. 24.3 Ω B. 28.3 Ω C. 33.3 Ω D. 38.3 Ω

C. 33.3 Ω

Calculate the total impedance of a parallel RC circuit if R = XC = 50Ω. A. 25 @ 45° Ω B. 25 @ -45° Ω C. 35.35 @ 45° Ω D. 35.35 @ -45° Ω

D. 35.35 @ -45° Ω

A 100-volt source is supplying a parallel RC circuit having a total impedance of 35.35Ω. Calculate the total line current. A. 2.83 45° B. 2.83 -45° C. 4.00 45° D. 4.00 -45°

A. 2.83 45°

What is the power factor of a circuit if the inductive susceptance and conductance have the same value? A. 0.325 B. 0.525 C. 0.673 D. 0.707

D. 0.707

If a circuit has an admittance of Y = 0.2 + j0.6, the circuit is A. purely inductive B. inductive C. capacitive D. reactive

C. capacitive

The circuit admittance Y = 0.2 - j0.6, the circuit is A. resistive B. inductive C. capacitive D. reactive

B. inductive

What is the resonant frequency of a circuit when L is 50 microhenrys and C is 40 picofarads are in parallel? A. 7.96 MHz B. 79.6 MHz C. 3.56 MHz D. 1.78 MHz

C. 3.56 MHz

If you need an LC circuit to be resonant at 2500 Hz and use a 150 mH coil, what should the capacitance value be? A. 0.027 μF B. 0.015 μF C. 0.15 μF D. 27 μF

A. 0.027 μF

What is the resonant frequency of a circuit when L of 3 microhenry and C of 40 picofarad are in series? A. 1.33 MHz B. 14.5 MHz C. 14.5 kHz D. 1.33 kHz

B. 14.5 MHz

What is the resonant frequency of a circuit when L of 25 microhenry and C of 10 picofarad are in parallel? A. 63.7 MHz B. 10.1 MHz C. 63.7 kHz D. 10.1 kHz

B. 10.1 MHz

A series circuit at resonance would mean, the circuit is A. resistive B. inductive C. capacitive D. reactive

A. resistive

Characteristics of the current in a series R-L-C circuit at resonance. A. It is dc B. It is a minimum C. It is zero D. It is at maximum

D. It is at maximum

What is the cause of a minimum Q on a single-tuned LC circuit? A. decreased series resistor B. decreased shunt resistor C. increased shunt resistor D. decreased capacitance

C. increased shunt resistor

Find the half-power bandwidth of a parallel resonant circuit, which has a resonant frequency of 3.6 MHz and a Q of 218. A. 606 kHz B. 58.7 kHz C. 16.5 kHz D. 47.3 kHz

C. 16.5 kHz

A parallel circuit at resonance would mean, the circuit is A. resistive B. inductive C. reactive D. capacitive

A. resistive

What will happen to a parallel ac-circuit if its line frequency is more than the resonant frequency? A. becomes purely resistive B. becomes purely capacitive C. becomes inductive D. becomes capacitive

D. becomes capacitive

In a series ac-circuit, if the line frequency is more than the resonant frequency, the circuit behaves as A. resistive B. inductive C. reactive D. capacitive

B. inductive

If the line frequency of a parallel ac-circuit is less than the resonant frequency, the circuit behaves as A. resistive B. reactive C. capacitive D. purely inductive

B. reactive

If an ac-series circuit is supplied with a source whose frequency is less than that of fr, the circuit becomes A. resistive B. reactive C. inductive D. capacitive

D. capacitive

_________ is a parallel LC circuit. A. Parallel resisting circuit B. Static circuit C. Tank circuit D. Hartley circuit

C. Tank circuit

A parallel LC network with L = 100 mH and C = 25μF will resonate at what frequency? A. 25 Hz B. 45.5 Hz C. 75.6 Hz D. 100 Hz

D. 100 Hz

Absolutely, when can we say that the circuit is at resonance? A. when XL = XC B. when the current is minimum C. when the voltage and current are in-phase D. all of the above

C. when the voltage and current are in-phase

Test 2 Flashcards

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