Electrical Principles 1 G5 - ELECTRICAL PRINCIPLES [3 exam questions - 3 groups] G5AResistance;...

Electrical Principles1

G5 - ELECTRICAL PRINCIPLES G5 - ELECTRICAL PRINCIPLES [3 exam questions - 3 groups] [3 exam questions - 3 groups]

G5AG5A Resistance; reactance; inductance; capacitance; Resistance; reactance; inductance; capacitance; impedance; impedance matching impedance; impedance matching

G5BG5B The Decibel; current and voltage dividers; The Decibel; current and voltage dividers; electrical power calculations; sine wave root-electrical power calculations; sine wave root-mean-square (RMS) values; PEP calculationsmean-square (RMS) values; PEP calculations

G5CG5C Resistors, capacitors, and inductors in series and Resistors, capacitors, and inductors in series and parallel; transformers parallel; transformers

Resistance, Impedance and ReactanceResistance, Impedance and Reactance

RESISTANCERESISTANCE IS THE OPPOSITION TO THE FLOW OF DIRECT IS THE OPPOSITION TO THE FLOW OF DIRECT CURRENT (DC). REPRESENTED AS THE LETTER RCURRENT (DC). REPRESENTED AS THE LETTER R

REACTANCEREACTANCE IS THE OPPOSITION TO THE FLOW OF IS THE OPPOSITION TO THE FLOW OF ALTERNATING CURRENT (AC) THAT A CAPACITOR OR ALTERNATING CURRENT (AC) THAT A CAPACITOR OR INDUCTOR PRESENTS. REPRESENTED AS THE LETTER ZINDUCTOR PRESENTS. REPRESENTED AS THE LETTER Z

IMPEDANCEIMPEDANCE IS THE OPPOSITION TO THE FLOW OF IS THE OPPOSITION TO THE FLOW OF ALTERNAING CURRENT (AC) AND VARIES AS FREQUENCY ALTERNAING CURRENT (AC) AND VARIES AS FREQUENCY VARIES AND MAY INCLUDE XVARIES AND MAY INCLUDE XL L , X, XCC AND R COMPONENTS. AND R COMPONENTS.



G5A01 What is impedance?G5A01 What is impedance?

A.A. The electric charge stored by a capacitorThe electric charge stored by a capacitor

B.B. The inverse of resistanceThe inverse of resistance

C.C. The opposition to the flow of current in an AC circuitThe opposition to the flow of current in an AC circuit

D.D. The force of repulsion between two similar electric The force of repulsion between two similar electric fieldsfields


G5A01 What is impedance?G5A01 What is impedance?

A.A. The electric charge stored by a capacitorThe electric charge stored by a capacitor

B.B. The inverse of resistanceThe inverse of resistance

C.C. The opposition to the flow of current in an The opposition to the flow of current in an AC circuitAC circuit

D.D. The force of repulsion between two similar electric The force of repulsion between two similar electric fieldsfields


Resonant CircuitResonant Circuit“Reactance”“Reactance”


G5A02 What is reactance?G5A02 What is reactance?

A.A. Opposition to the flow of direct current caused by Opposition to the flow of direct current caused by resistanceresistance

B.B. Opposition to the flow of alternating current caused Opposition to the flow of alternating current caused by capacitance or inductanceby capacitance or inductance

C.C. A property of ideal resistors in AC circuitsA property of ideal resistors in AC circuits

D.D. A large spark produced at switch contacts when an A large spark produced at switch contacts when an inductor is de-energizedinductor is de-energized


G5A02 What is reactance?G5A02 What is reactance?

A.A. Opposition to the flow of direct current caused by Opposition to the flow of direct current caused by resistanceresistance

B.B. Opposition to the flow of alternating Opposition to the flow of alternating current caused by capacitance or inductancecurrent caused by capacitance or inductance

C.C. A property of ideal resistors in AC circuitsA property of ideal resistors in AC circuits

D.D. A large spark produced at switch contacts when an A large spark produced at switch contacts when an inductor is de-energizedinductor is de-energized


G5A03 Which of the following causes G5A03 Which of the following causes opposition to the flow of alternating opposition to the flow of alternating current in an inductor?current in an inductor?

A.A. ConductanceConductance

B.B. ReluctanceReluctance

C.C. AdmittanceAdmittance

D.D. ReactanceReactance


G5A03 Which of the following causes G5A03 Which of the following causes opposition to the flow of alternating opposition to the flow of alternating current in an inductor?current in an inductor?



C.C. AdmittanceAdmittance

D.D. ReactanceReactance

Inductor is also called a Coil Inductor is also called a Coil


G5A04 Which of the following causes G5A04 Which of the following causes opposition to the flow of alternating opposition to the flow of alternating current in a capacitor?current in a capacitor?



C.C. ReactanceReactance

D.D. AdmittanceAdmittance


G5A04 Which of the following causes G5A04 Which of the following causes opposition to the flow of alternating opposition to the flow of alternating current in a capacitor?current in a capacitor?



C.C. ReactanceReactanceD.D. AdmittanceAdmittance


G5A05 How does a coil react to AC?G5A05 How does a coil react to AC?

A.A. As the frequency of the applied AC increases, the As the frequency of the applied AC increases, the reactance decreasesreactance decreases

B.B. As the amplitude of the applied AC increases, the As the amplitude of the applied AC increases, the reactance increasesreactance increases

C.C. As the amplitude of the applied AC increases, the As the amplitude of the applied AC increases, the reactance decreasesreactance decreases

D.D. As the frequency of the applied AC increases, the As the frequency of the applied AC increases, the reactance increasesreactance increases


G5A05 How does a coil react to AC?G5A05 How does a coil react to AC?

D.D. As the frequency of the applied AC As the frequency of the applied AC increases, the reactance increasesincreases, the reactance increases


G5A06 How does a capacitor react to G5A06 How does a capacitor react to AC?AC?

A.A. As the frequency of the applied AC increases, the As the frequency of the applied AC increases, the reactance decreasesreactance decreases

B.B. As the frequency of the applied AC increases, the As the frequency of the applied AC increases, the reactance increasesreactance increases

C.C. As the amplitude of the applied AC increases, the As the amplitude of the applied AC increases, the reactance increasesreactance increases

D.D. As the amplitude of the applied AC increases, the As the amplitude of the applied AC increases, the reactance decreasesreactance decreases


G5A06 How does a capacitor react to G5A06 How does a capacitor react to AC?AC?

A.A. As the frequency of the applied AC As the frequency of the applied AC increases, the reactance decreasesincreases, the reactance decreases


G5A07 What happens when the G5A07 What happens when the impedance of an electrical load is equal impedance of an electrical load is equal to the internal impedance of the power to the internal impedance of the power source?source?

A.A. The source delivers minimum power to the loadThe source delivers minimum power to the load

B.B. The electrical load is shortedThe electrical load is shorted

C.C. No current can flow through the circuitNo current can flow through the circuit

D.D. The source can deliver maximum power to the loadThe source can deliver maximum power to the load


G5A07 What happens when the G5A07 What happens when the impedance of an electrical load is equal impedance of an electrical load is equal to the internal impedance of the power to the internal impedance of the power source?source?

A.A. The source delivers minimum power to the loadThe source delivers minimum power to the load

B.B. The electrical load is shortedThe electrical load is shorted

C.C. No current can flow through the circuitNo current can flow through the circuit

D.D. The source can deliver maximum power to The source can deliver maximum power to the loadthe load


G5A08 Why is impedance matching G5A08 Why is impedance matching important?important?

A.A. So the source can deliver maximum power to the So the source can deliver maximum power to the loadload

B.B. So the load will draw minimum power from the So the load will draw minimum power from the sourcesource

C.C. To ensure that there is less resistance than To ensure that there is less resistance than reactance in the circuitreactance in the circuit

D.D. To ensure that the resistance and reactance in the To ensure that the resistance and reactance in the circuit are equalcircuit are equal


G5A08 Why is impedance matching G5A08 Why is impedance matching important?important?

A.A. So the source can deliver maximum power So the source can deliver maximum power to the loadto the load

B.B. So the load will draw minimum power from the So the load will draw minimum power from the sourcesource

C.C. To ensure that there is less resistance than To ensure that there is less resistance than reactance in the circuitreactance in the circuit

D.D. To ensure that the resistance and reactance in the To ensure that the resistance and reactance in the circuit are equalcircuit are equal


G5A09 What unit is used to measure G5A09 What unit is used to measure reactance?reactance?

A.A. FaradFarad

B.B. OhmOhm

C.C. AmpereAmpere

D.D. SiemensSiemens


G5A09 What unit is used to measure G5A09 What unit is used to measure reactance?reactance?

A.A. FaradFarad

B.B. Ohm Ohm C.C. AmpereAmpere

D.D. SiemensSiemens

Ohm is also used to measure resistance.Ohm is also used to measure resistance.


G5A10 What unit is used to measure G5A10 What unit is used to measure impedance?impedance?

A.A. VoltVolt

B.B. OhmOhm

C.C. AmpereAmpere

D.D. WattWatt


G5A10 What unit is used to measure G5A10 What unit is used to measure impedance?impedance?

A.A. VoltVolt

B.B. OhmOhmC.C. AmpereAmpere

D.D. WattWatt

Same unit of measurement for Reactance, Same unit of measurement for Reactance, Resistance, Impedance.Resistance, Impedance.


G5A11 Why should core saturation of a G5A11 Why should core saturation of a conventional impedance matching conventional impedance matching transformer be avoided?transformer be avoided?

A.A. Harmonics and distortion could resultHarmonics and distortion could result

B.B. Magnetic flux would increase with frequencyMagnetic flux would increase with frequency

C.C. RF susceptance would increaseRF susceptance would increase

D.D. Temporary changes of the core permeability could Temporary changes of the core permeability could resultresult


G5A11 Why should core saturation of a G5A11 Why should core saturation of a conventional impedance matching conventional impedance matching transformer be avoided?transformer be avoided?

A.A. Harmonics and distortion could resultHarmonics and distortion could result

B.B. Magnetic flux would increase with frequencyMagnetic flux would increase with frequency

C.C. RF susceptance would increaseRF susceptance would increase

D.D. Temporary changes of the core permeability could resultTemporary changes of the core permeability could result


G5A12 What is one reason to use an G5A12 What is one reason to use an impedance matching transformer?impedance matching transformer?

A.A. To reduce power dissipation in the transmitterTo reduce power dissipation in the transmitter

B.B. To maximize the transfer of powerTo maximize the transfer of power

C.C. To minimize SWR at the antennaTo minimize SWR at the antenna

D.D. To minimize SWR in the transmission lineTo minimize SWR in the transmission line


G5A12 What is one reason to use an G5A12 What is one reason to use an impedance matching transformer?impedance matching transformer?

A.A. To reduce power dissipation in the transmitterTo reduce power dissipation in the transmitter

B.B. To maximize the transfer of powerTo maximize the transfer of powerC.C. To minimize SWR at the antennaTo minimize SWR at the antenna

D.D. To minimize SWR in the transmission lineTo minimize SWR in the transmission line

Impedance MatchingImpedance Matching



G5A13 Which of the following devices G5A13 Which of the following devices can be used for impedance matching at can be used for impedance matching at radio frequencies?radio frequencies?

A.A. A transformerA transformer

B.B. A Pi-networkA Pi-network

C.C. A length of transmission lineA length of transmission line

D.D. All of these choices are correctAll of these choices are correct


G5A14 Which of the following describes G5A14 Which of the following describes one method of impedance matching one method of impedance matching between two AC circuits?between two AC circuits?

A.A. Insert an LC network between the two circuitsInsert an LC network between the two circuits

B.B. Reduce the power output of the first circuitReduce the power output of the first circuit

C.C. Increase the power output of the first circuitIncrease the power output of the first circuit

D.D. Insert a circulator between the two circuitsInsert a circulator between the two circuits


G5A14 Which of the following describes G5A14 Which of the following describes one method of impedance matching one method of impedance matching between two AC circuits?between two AC circuits?

A.A. Insert an LC network between the two Insert an LC network between the two circuitscircuits

B.B. Reduce the power output of the first circuitReduce the power output of the first circuit

C.C. Increase the power output of the first circuitIncrease the power output of the first circuit

D.D. Insert a circulator between the two circuitsInsert a circulator between the two circuits

Amateur Radio Practices33

Decibel MultipliersDecibel Multipliers

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The Decibel scale is logarithmic. 3dB represents a 2-fold increase in power, 6dB is 4 fold, 10dB is 10-fold, 20dB is 100-fold. The S-Unit scale on a receiver meter is not an absolute scale and can vary from radio to radio. Although these meters are not calibrated, they can be useful for verifying antenna performance. One “S-Unit” represents a 4-fold change in power or 6dB.


G5B01 A two-times increase or G5B01 A two-times increase or decrease in power results in a change decrease in power results in a change of how many dB?of how many dB?

A.A. 2 dB2 dB

B.B. 3 dB3 dB

C.C. 6 dB6 dB

D.D. 12 dB12 dB


G5B01 A two-times increase or G5B01 A two-times increase or decrease in power results in a change decrease in power results in a change of how many dB?of how many dB?

A.A. 2 dB2 dB

B.B. 3 dB3 dBC.C. 6 dB6 dB

D.D. 12 dB12 dB

Pm Pm db=10log db=10log1010 ------ ------ Pref Pref

Pm = Measured Power, Pref = Reference PowerPm = Measured Power, Pref = Reference Power


G5B02 How does the total current G5B02 How does the total current relate to the individual currents in each relate to the individual currents in each branch of a parallel circuit?branch of a parallel circuit?

A.A. It equals the average of each branch currentIt equals the average of each branch current

B.B. It decreases as more parallel branches are added to It decreases as more parallel branches are added to the circuitthe circuit

C.C. It equals the sum of the currents through each It equals the sum of the currents through each branchbranch

D.D. It is the sum of the reciprocal of each individual It is the sum of the reciprocal of each individual voltage dropvoltage drop


G5B02 How does the total current G5B02 How does the total current relate to the individual currents in each relate to the individual currents in each branch of a parallel circuit?branch of a parallel circuit?

A.A. It equals the average of each branch currentIt equals the average of each branch current

B.B. It decreases as more parallel branches are added to It decreases as more parallel branches are added to the circuitthe circuit

C.C. It equals the sum of the currents through It equals the sum of the currents through each brancheach branch

D.D. It is the sum of the reciprocal of each individual It is the sum of the reciprocal of each individual voltage dropvoltage drop


Ohm’s Law and Power CalculationsOhm’s Law and Power Calculations

E

I R

P

I EE=Voltage (Volts)

I=Current (Amps)

R=Resistance (Ohms)

P=Power (Watts)

E = I * R P = I * E


G5B03 How many watts of electrical G5B03 How many watts of electrical power are used if 400 VDC is supplied power are used if 400 VDC is supplied to an 800-ohm load?to an 800-ohm load?

A.A. 0.5 watts0.5 watts

B.B. 200 watts200 watts

C.C. 400 watts400 watts

D.D. 3200 watts3200 watts


G5B03 How many watts of electrical G5B03 How many watts of electrical power are used if 400 VDC is supplied power are used if 400 VDC is supplied to an 800-ohm load?to an 800-ohm load?


B.B. 200 watts200 wattsC.C. 400 watts400 watts


P = E P = E22 / R / R P = 160,000 / 800 P = 160,000 / 800 P = 200 watts P = 200 watts

E

I R


G5B04 How many watts of electrical G5B04 How many watts of electrical power are used by a 12-VDC light bulb power are used by a 12-VDC light bulb that draws 0.2 amperes?that draws 0.2 amperes?



C.C. 6 watts6 watts


P

I E


G5B04 How many watts of electrical G5B04 How many watts of electrical power are used by a 12-VDC light bulb power are used by a 12-VDC light bulb that draws 0.2 amperes?that draws 0.2 amperes?

A.A. 2.4 watts2.4 wattsB.B. 24 watts24 watts

C.C. 6 watts6 watts


P = I * E P = I * E P = .2 * 12 P = .2 * 12 P = 2.4 watts P = 2.4 watts

P

I E


G5B05 How many watts are being G5B05 How many watts are being dissipated when a current of 7.0 dissipated when a current of 7.0 milliamperes flows through 1.25 milliamperes flows through 1.25 kilohms?kilohms?

A.A. Approximately 61 milliwattsApproximately 61 milliwatts

B.B. Approximately 39 milliwattsApproximately 39 milliwatts

C.C. Approximately 11 milliwattsApproximately 11 milliwatts

D.D. Approximately 9 milliwattsApproximately 9 milliwatts


G5B05 How many watts are being G5B05 How many watts are being dissipated when a current of 7.0 dissipated when a current of 7.0 milliamperes flows through 1.25 milliamperes flows through 1.25 kilohms?kilohms?

A.A. Approximately 61 milliwattsApproximately 61 milliwattsB.B. Approximately 39 milliwattsApproximately 39 milliwatts

C.C. Approximately 11 milliwattsApproximately 11 milliwatts

D.D. Approximately 9 milliwattsApproximately 9 milliwatts

P=I * I * R P=I * I * R P= I P= I22 * R * R P = .007*.007 * 1250 P = .007*.007 * 1250 P= .06125 = 61 milliwatts P= .06125 = 61 milliwatts

E

I R


RMS, Peak and Peak to Peak VoltagesRMS, Peak and Peak to Peak Voltages

There are three key voltage measurements, RMS (Vrms), Peak (Vpk) and Peak to Peak (Vpp).



The Peak voltage is relative to ground.



RMS or Root Mean Square is more of an “average” voltage over the duration of the AC cycle. RMS voltage is calculated by multiplying 0.707 times the peak voltage.



The Peak to Peak voltage measures from the peak of the positive swing to the peak of the negative swing.

PEPPEPPeak envelope power is the average Peak envelope power is the average power supplied supplied

to the to the antenna transmission line by a by a transmitter during one during one radio frequency cycle at the crest of cycle at the crest of the the modulation envelope, under normal operating , under normal operating conditions.conditions.

PEP was often used in non-PEP was often used in non-broadcast amplitude modulation (AM) applications because it (AM) applications because it most accurately described the potential of mobile most accurately described the potential of mobile transmitters to interfere with each other. Its use is transmitters to interfere with each other. Its use is now somewhat now somewhat deprecated, with the , with the averageaverage transmitter power output (or sometimes (or sometimes effective radiated power) now typically being ) now typically being preferred.preferred.



G5B06 What is the output PEP from a G5B06 What is the output PEP from a transmitter if an oscilloscope measures transmitter if an oscilloscope measures 200 volts peak-to-peak across a 50-ohm 200 volts peak-to-peak across a 50-ohm dummy load connected to the dummy load connected to the transmitter output?transmitter output?



C.C. 353.5 watts353.5 watts



G5B06 What is the output PEP from a G5B06 What is the output PEP from a transmitter if an oscilloscope measures transmitter if an oscilloscope measures 200 volts peak-to-peak across a 50-ohm 200 volts peak-to-peak across a 50-ohm dummy load connected to the dummy load connected to the transmitter output?transmitter output?


B.B. 100 watts100 wattsC.C. 353.5 watts353.5 watts


PEP = ((V PEP = ((Vpppp/2)*.707)/2)*.707)22

------------------- -------------------

RRLoadLoad


G5B07 Which measurement of an AC G5B07 Which measurement of an AC signal is equivalent to a DC voltage of signal is equivalent to a DC voltage of the same value?the same value?

A.A. The peak-to-peak valueThe peak-to-peak value

B.B. The peak valueThe peak value

C.C. The RMS valueThe RMS value

D.D. The reciprocal of the RMS valueThe reciprocal of the RMS value


G5B07 Which measurement of an AC G5B07 Which measurement of an AC signal is equivalent to a DC voltage of signal is equivalent to a DC voltage of the same value?the same value?

A.A. The peak-to-peak valueThe peak-to-peak value

B.B. The peak valueThe peak value

C.C. The RMS valueThe RMS valueD.D. The reciprocal of the RMS valueThe reciprocal of the RMS value


G5B08 What is the peak-to-peak G5B08 What is the peak-to-peak voltage of a sine wave that has an RMS voltage of a sine wave that has an RMS voltage of 120 volts?voltage of 120 volts?

A.A. 84.8 volts84.8 volts

B.B. 169.7 volts169.7 volts

C.C. 240.0 volts240.0 volts

D.D. 339.4 volts339.4 volts







Peak Voltage = RMS *1/.707Peak Voltage = RMS * 1.414Peak Voltage = 169.68Peak to Peak = 169.68 * 2Peak to Peak = 339.4


G5B09 What is the RMS voltage of sine G5B09 What is the RMS voltage of sine wave with a value of 17 volts peak?wave with a value of 17 volts peak?


B.B. 12 volts12 volts

C.C. 24 volts24 volts

D.D. 34 volts34 volts


G5B09 What is the RMS voltage of sine G5B09 What is the RMS voltage of sine wave with a value of 17 volts peak?wave with a value of 17 volts peak?


B.B. 12 volts12 voltsC.C. 24 volts24 volts



G5B11 What is the ratio of peak G5B11 What is the ratio of peak envelope power to average power for envelope power to average power for an unmodulated carrier?an unmodulated carrier?

A.A. .707.707

B.B. 1.001.00

C.C. 1.4141.414

D.D. 2.002.00


G5B11 What is the ratio of peak G5B11 What is the ratio of peak envelope power to average power for envelope power to average power for an unmodulated carrier?an unmodulated carrier?

A.A. .707.707

B.B. 1.001.00C.C. 1.4141.414

D.D. 2.002.00


G5B12 What would be the voltage G5B12 What would be the voltage across a 50-ohm dummy load across a 50-ohm dummy load dissipating 1200 watts?dissipating 1200 watts?

A.A. 173 volts173 volts


C.C. 346 volts346 volts



G5B12 What would be the voltage G5B12 What would be the voltage across a 50-ohm dummy load across a 50-ohm dummy load dissipating 1200 watts?dissipating 1200 watts?


B.B. 245 volts245 voltsC.C. 346 volts346 volts


E E rms rms = PEP *R = PEP *R


G5B13 What percentage of power loss G5B13 What percentage of power loss would result from a transmission line would result from a transmission line loss of 1 dB?loss of 1 dB?

A.A. 10.9 %10.9 %

B.B. 12.2 %12.2 %

C.C. 20.5 %20.5 %

D.D. 25.9 %25.9 %


G5B13 What percentage of power loss G5B13 What percentage of power loss would result from a transmission line would result from a transmission line loss of 1 dB?loss of 1 dB?

A.A. 10.9 %10.9 %

B.B. 12.2 %12.2 %

C.C. 20.5 %20.5 %D.D. 25.9 %25.9 %

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G5B14 What is the output PEP from a G5B14 What is the output PEP from a transmitter if an oscilloscope measures transmitter if an oscilloscope measures 500 volts peak-to-peak across a 50-ohm 500 volts peak-to-peak across a 50-ohm resistor connected to the transmitter resistor connected to the transmitter output?output?






G5B14 What is the output PEP from a G5B14 What is the output PEP from a transmitter if an oscilloscope measures transmitter if an oscilloscope measures 500 volts peak-to-peak across a 50-ohm 500 volts peak-to-peak across a 50-ohm resistor connected to the transmitter resistor connected to the transmitter output?output?




PEP = ((Vpp/2)*.707)2

------------------- RLoad


G5B15 What is the output PEP of an G5B15 What is the output PEP of an unmodulated carrier if an average unmodulated carrier if an average reading wattmeter connected to the reading wattmeter connected to the transmitter output indicates 1060 transmitter output indicates 1060 watts?watts?

A.A. 530 watts530 watts




InductanceInductance


Inductance is the property in an electrical circuit where a change in the electric current through that circuit induces an electromotive force (EMF) that opposes the change in current (See Induced EMF).


G5C01 What causes a voltage to appear G5C01 What causes a voltage to appear across the secondary winding of a across the secondary winding of a transformer when an AC voltage source transformer when an AC voltage source is connected across its primary is connected across its primary winding?winding?

A.A. Capacitive couplingCapacitive coupling

B.B. Displacement current couplingDisplacement current coupling

C.C. Mutual inductanceMutual inductance

D.D. Mutual capacitanceMutual capacitance


G5C01 What causes a voltage to appear G5C01 What causes a voltage to appear across the secondary winding of a across the secondary winding of a transformer when an AC voltage source transformer when an AC voltage source is connected across its primary is connected across its primary winding?winding?

A.A. Capacitive couplingCapacitive coupling

B.B. Displacement current couplingDisplacement current coupling

C.C. Mutual inductanceMutual inductanceD.D. Mutual capacitanceMutual capacitance


G5C02 Where is the source of energy G5C02 Where is the source of energy normally connected in a transformer?normally connected in a transformer?

A.A. To the secondary windingTo the secondary winding

B.B. To the primary windingTo the primary winding

C.C. To the coreTo the core

D.D. To the platesTo the plates


G5C02 Where is the source of energy G5C02 Where is the source of energy normally connected in a transformer?normally connected in a transformer?

A.A. To the secondary windingTo the secondary winding

B.B. To the primary windingTo the primary windingC.C. To the coreTo the core

D.D. To the platesTo the plates


G5C03 What is current in the primary G5C03 What is current in the primary winding of a transformer called if no winding of a transformer called if no load is attached to the secondary?load is attached to the secondary?

A.A. Magnetizing currentMagnetizing current

B.B. Direct currentDirect current

C.C. Excitation currentExcitation current

D.D. Stabilizing currentStabilizing current


G5C03 What is current in the primary G5C03 What is current in the primary winding of a transformer called if no winding of a transformer called if no load is attached to the secondary?load is attached to the secondary?

A.A. Magnetizing currentMagnetizing currentB.B. Direct currentDirect current

C.C. Excitation currentExcitation current

D.D. Stabilizing currentStabilizing current

Resistors in Series

Resistors in Series are additive.

RT = R1 + R2 + R3 +RN….

Resistors in Parallel

When Resistors are connected in parallel, their combined resistance is less than the resistance of the smallest

resistor. R1*R2

Two Resistors formula RT = --------- (Product of over Sum) R1+R2

1 1 1 1 1

Two or more.. -- = -- + -- + -- + --

(Reciprocal) RT R1 R2 R3 R……


G5C04 What is the total resistance of G5C04 What is the total resistance of three 100-ohm resistors in parallel?three 100-ohm resistors in parallel?

A.A. .30 ohms.30 ohms

B.B. .33 ohms.33 ohms

C.C. 33.3 ohms33.3 ohms

D.D. 300 ohms300 ohms


G5C04 What is the total resistance of G5C04 What is the total resistance of three 100-ohm resistors in parallel?three 100-ohm resistors in parallel?

A.A. .30 ohms.30 ohms

B.B. .33 ohms.33 ohms

C.C. 33.3 ohms33.3 ohmsD.D. 300 ohms300 ohms


G5C05 What is the value of each G5C05 What is the value of each resistor if three equal value resistors in resistor if three equal value resistors in parallel produce 50 ohms of resistance, parallel produce 50 ohms of resistance, and the same three resistors in series and the same three resistors in series produce 450 ohms?produce 450 ohms?

A.A. 1500 ohms1500 ohms

B.B. 90 ohms90 ohms

C.C. 150 ohms150 ohms

D.D. 175 ohms175 ohms


G5C05 What is the value of each G5C05 What is the value of each resistor if three equal value resistors in resistor if three equal value resistors in parallel produce 50 ohms of resistance, parallel produce 50 ohms of resistance, and the same three resistors in series and the same three resistors in series produce 450 ohms?produce 450 ohms?

A.A. 1500 ohms1500 ohms

B.B. 90 ohms90 ohms

C.C. 150 ohms150 ohmsD.D. 175 ohms175 ohms

Transformers Isolation / Matching

Isolation – Unity turns ratio Same number of turns in the secondary

as in the primary.

MatchingStep Up or Step Down Step up… More windings in

Secondary Step Down…More windings in Primary

Calculating Turns Ratio

Each winding of a transformer contains a certain number of turns of wire. The turns ratio is defined

as the ratio of turns of wire in the primary winding to the number of turns of wire in the secondary

winding. Turns ratio can be expressed using the formula

Np

Ratio = ------ Ns

Np = Number of turns in the PrimaryNs = Number of turns in the Secondary


G5C06 What is the voltage across a G5C06 What is the voltage across a 500-turn secondary winding in a 500-turn secondary winding in a transformer if the 2250-turn primary is transformer if the 2250-turn primary is connected to 120 VAC?connected to 120 VAC?






G5C06 What is the voltage across a G5C06 What is the voltage across a 500-turn secondary winding in a 500-turn secondary winding in a transformer if the 2250-turn primary is transformer if the 2250-turn primary is connected to 120 VAC?connected to 120 VAC?



C.C. 26.7 volts26.7 voltsD.D. 5.9 volts5.9 volts

Impedance MatchingMaximum power is transferred from one circuit to

another through a transformer when the impedances are equal, or matched. A transformer winding constructed with a definite turns ratio can perform an impedance matching function. The turns ratio will establish the proper relationship between the primary and secondary winding impedances.

The ratio between the two impedances is referred to as the impedance ratio and is expressed by using the following equation.

Np Zp --- = ---- Ns Zs

Where Np = Number of turns in Primary Ns = Number of turns in Secondary Zp = Impedance of Primary Zs = Impedance of Secondary


G5C07 What is the turns ratio of a G5C07 What is the turns ratio of a transformer used to match an audio transformer used to match an audio amplifier having a 600-ohm output amplifier having a 600-ohm output impedance to a speaker having a 4-ohm impedance to a speaker having a 4-ohm impedance?impedance?

A.A. 12.2 to 112.2 to 1

B.B. 24.4 to 124.4 to 1

C.C. 150 to 1150 to 1

D.D. 300 to 1300 to 1


G5C07 What is the turns ratio of a G5C07 What is the turns ratio of a transformer used to match an audio transformer used to match an audio amplifier having a 600-ohm output amplifier having a 600-ohm output impedance to a speaker having a 4-ohm impedance to a speaker having a 4-ohm impedance?impedance?

A.A. 12.2 to 112.2 to 1B.B. 24.4 to 124.4 to 1

C.C. 150 to 1150 to 1

D.D. 300 to 1300 to 1

Capacitors in Series

When capacitors are connected in series, the total capacitance is less than any one of the series capacitors' individual capacitances. If two or more capacitors are connected in series, the overall effect is that of a single (equivalent) capacitor having the sum total of the plate spacings of the individual capacitors. An increase in plate spacing, with all other factors unchanged, results in decreased capacitance. C1*C2 Two Capacitors CT = --------- C1+C2

Two or more.. 1 1 1 1 1 -- = -- + -- + -- + -- CT C1 C2 C3 C……

Capacitors in Parallel

When capacitors are connected in parallel, the total capacitance is the sum of the individual capacitors' capacitances. If two or more capacitors are connected in parallel, the overall effect is that of a single equivalent capacitor having the sum total of the plate areas of the individual capacitors. An increase in plate area, with all other factors unchanged, results in increased capacitance.

Capacitors in Parallel are additive.

CT = C1 + C 2 + C3 +C...

Inductors in SeriesWhen inductors are connected in series, the total inductance

is the sum of the individual inductors' inductances. The definitive measure of inductance is the amount of voltage dropped across an inductor for a given rate of current change through it. If inductors are connected together in series (thus sharing the same current, and seeing the same rate of change in current), then the total voltage dropped as the result of a change in current will be additive with each inductor, creating a greater total voltage than either of the individual inductors alone. Greater voltage for the same rate of change in current means greater inductance.

Inductors in Series are additive.

LT = L1 + L 2 + L3 +L...

Inductors in ParallelWhen inductors are connected in parallel, the total inductance is

less than any one of the parallel inductors' inductances. Rremember that the definitive measure of inductance is the amount of voltage dropped across an inductor for a given rate of current change through it. Since the current through each parallel inductor will be a fraction of the total current, and the voltage across each parallel inductor will be equal, a change in total current will result in less voltage dropped across the parallel array than for any one of the inductors considered separately. In other words, there will be less voltage dropped across parallel inductors for a given rate of change in current than for any of those inductors considered separately, because total current divides among parallel branches. Less voltage for the same rate of change in current means less inductance.

1 1 1 1 1Two or more.. -- = -- + -- + -- + --(Reciprocal) LT L1 L2 L3 L……


G5C08 What is the equivalent G5C08 What is the equivalent capacitance of two 5000 picofarad capacitance of two 5000 picofarad capacitors and one 750 picofarad capacitors and one 750 picofarad capacitor connected in capacitor connected in parallelparallel??

A.A. 576.9 picofarads576.9 picofarads

B.B. 1733 picofarads1733 picofarads

C.C. 3583 picofarads3583 picofarads

D.D. 10750 picofarads10750 picofarads


G5C08 What is the equivalent G5C08 What is the equivalent capacitance of two 5000 picofarad capacitance of two 5000 picofarad capacitors and one 750 picofarad capacitors and one 750 picofarad capacitor connected in parallel?capacitor connected in parallel?

A.A. 576.9 picofarads576.9 picofarads

B.B. 1733 picofarads1733 picofarads

C.C. 3583 picofarads3583 picofarads

D.D. 10750 picofarads10750 picofarads


G5C09 What is the capacitance of three G5C09 What is the capacitance of three 100 microfarad capacitors connected in 100 microfarad capacitors connected in series?series?

A.A. .30 microfarads.30 microfarads

B.B. .33 microfarads.33 microfarads

C.C. 33.3 microfarads33.3 microfarads

D.D. 300 microfarads300 microfarads


G5C09 What is the capacitance of three G5C09 What is the capacitance of three 100 microfarad capacitors connected in 100 microfarad capacitors connected in series?series?


B.B. .33 microfarads.33 microfarads

C.C. 33.3 microfarads33.3 microfaradsD.D. 300 microfarads300 microfarads


G5C10 What is the inductance of three G5C10 What is the inductance of three 10 millihenry inductors connected in 10 millihenry inductors connected in parallel?parallel?

A.A. .30 Henrys.30 Henrys

B.B. 3.3 Henrys3.3 Henrys

C.C. 3.3 millihenrys3.3 millihenrys

D.D. 30 millihenrys30 millihenrys


G5C10 What is the inductance of three G5C10 What is the inductance of three 10 millihenry inductors connected in 10 millihenry inductors connected in parallel?parallel?

C.C. 3.3 millihenrys3.3 millihenrys


G5C11 What is the inductance of a 20 G5C11 What is the inductance of a 20 millihenry inductor in millihenry inductor in seriesseries with a 50 with a 50 millihenry inductor?millihenry inductor?

A.A. .07 millihenrys.07 millihenrys

B.B. 14.3 millihenrys14.3 millihenrys

C.C. 70 millihenrys70 millihenrys

D.D. 1000 millihenrys1000 millihenrys


G5C11 What is the inductance of a 20 G5C11 What is the inductance of a 20 millihenry inductor in series with a 50 millihenry inductor in series with a 50 millihenry inductor?millihenry inductor?

A.A. .07 millihenrys.07 millihenrys

B.B. 14.3 millihenrys14.3 millihenrys

C.C. 70 millihenrys70 millihenrysD.D. 1000 millihenrys1000 millihenrys


G5C12 What is the capacitance of a 20 G5C12 What is the capacitance of a 20 microfarad capacitor in microfarad capacitor in seriesseries with a 50 with a 50 microfarad capacitor?microfarad capacitor?


B.B. 14.3 microfarads14.3 microfarads

C.C. 70 microfarads70 microfarads



G5C12 What is the capacitance of a 20 G5C12 What is the capacitance of a 20 microfarad capacitor in series with a 50 microfarad capacitor in series with a 50 microfarad capacitor?microfarad capacitor?


B.B. 14.3 microfarads14.3 microfaradsC.C. 70 microfarads70 microfarads



G5C13 What component should be G5C13 What component should be added to a capacitor in a circuit to added to a capacitor in a circuit to increase the circuit capacitance?increase the circuit capacitance?

A.A. An inductor in seriesAn inductor in series

B.B. A resistor in seriesA resistor in series

C.C. A capacitor in parallelA capacitor in parallel

D.D. A capacitor in seriesA capacitor in series


G5C13 What component should be G5C13 What component should be added to a capacitor in a circuit to added to a capacitor in a circuit to increase the circuit capacitance?increase the circuit capacitance?

A.A. An inductor in seriesAn inductor in series


C.C. A capacitor in parallelA capacitor in parallelD.D. A capacitor in seriesA capacitor in series


G5C14 What component should be G5C14 What component should be added to an inductor in a circuit to added to an inductor in a circuit to increase the circuit inductance?increase the circuit inductance?

A.A. A capacitor in seriesA capacitor in series

B.B. A resistor in parallelA resistor in parallel

C.C. An inductor in parallelAn inductor in parallel

D.D. An inductor in seriesAn inductor in series


G5C15 What is the total resistance of a G5C15 What is the total resistance of a 10 ohm, a 20 ohm, and a 50 ohm 10 ohm, a 20 ohm, and a 50 ohm resistor in resistor in parallelparallel??

A.A. 5.9 ohms5.9 ohms

B.B. 0.17 ohms0.17 ohms


D.D. 80 ohms80 ohms


G5C15 What is the total resistance of a G5C15 What is the total resistance of a 10 ohm, a 20 ohm, and a 50 ohm 10 ohm, a 20 ohm, and a 50 ohm resistor in parallel?resistor in parallel?

A.A. 5.9 ohms5.9 ohmsB.B. 0.17 ohms0.17 ohms


D.D. 80 ohms80 ohms


G5C16 What component should be G5C16 What component should be added to an existing resistor in a circuit added to an existing resistor in a circuit to increase circuit resistance?to increase circuit resistance?

A.A. A resistor in parallelA resistor in parallel


C.C. A capacitor in seriesA capacitor in series

D.D. A capacitor in parallelA capacitor in parallel


G5C16 What component should be G5C16 What component should be added to an existing resistor in a circuit added to an existing resistor in a circuit to increase circuit resistance?to increase circuit resistance?

A.A. A resistor in parallelA resistor in parallel

B.B. A resistor in seriesA resistor in seriesC.C. A capacitor in seriesA capacitor in series

D.D. A capacitor in parallelA capacitor in parallel


G5 - ELECTRICAL PRINCIPLES G5 - ELECTRICAL PRINCIPLES [3 exam questions - 3 groups][3 exam questions - 3 groups]

Electrical Principles 1 G5 - ELECTRICAL PRINCIPLES [3 exam questions - 3 groups] G5AResistance;...

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