Basic Electricity Flashcards
The working voltage of a capacitor in an AC circuit should be…
at least 50 percent greater than the highest applied voltage.
The term that describes the combined resistive forces in an AC circuit is…
impedance.
What is the opposition to the flow of AC produced by an electromagnetic field (EMF) with generated back voltage called?
Inductive reactance.
Electrostatic fields are also known as…
dielectric fields.
The basis for transformer operation in the use of alternating current is mutual.
inductance.
The opposition offered by a coil to the flow of alternating current (ignoring resistance) is called…
inductive reactance.
What factors strengthen a coil inductor?
Adding coils close together.
An increase in which of the following factors will cause an increase in the inductive reactance of a circuit?
Inductance and frequency.
When different rated capacitors are connected in series in a circuit, the total capacitance is…
less than the capacitance of the lowest rated capacitor.
Capacitors are sometimes used in DC circuits to…
smooth out slight pulsations in current/voltage.
In an AC circuit, the effective voltage is…
less than the maximum instantaneous voltage.
The amount of electricity a capacitor can store is directly proportional to the…
plate area and inversely proportional to the distance between the plates.
What is the total capacitance of a certain circuit containing three capacitors with capacitances of 0.02 microfarad, 0.05 microfarad, and 0.10 microfarad, respectively?
0.0125 microfarad.
What is the total capacitance of a circuit containing three capacitors in parallel with capacitances of 0.02 microfarad, 0.05 microfarad, and 0.10 microfarad, respectively?
0.170 microfarad.
Converts farad to microfarads by…
multiplying farads by 10 to the power of 6.
Convert farads to picofarads by…
multiplying farads by 10 to the power of 12.
Unless otherwise specified, any values given for current or voltage in an AC circuit are assumed to be…
effective values.
When different rated capacitors are connected in parallel in a circuit, the total capacitance is (Note: Ct = C1 + C2 + C3…)…
equal to the sum of all the capacitances.
When inductors are connected in series in a circuit, the total inductance (where the magnetic fields of each inductor do not affect the others) is… (Note: Lt = L1 + L2 + L3…)
equal to the sum of the individual inductances.
When more than two inductors of different inductances are connected in parallel in a circuit, the total inductance is…
less than the inductance of the lowest rated inductor.
What is the total capacitance of a certain circuit containing three capacitors with capacitances of 0.25 microfarad, 0.03 microfarad, and 0.12 microfarad, respectively? (Note: Ct = C1 + C2 + C3)
0.4 microfarad.
Which requires the most electrical power during operation? (Note: 1 horsepower = 746 watts)
Two lights requiring 3 amperes each in a 24-volt parallel system.
450 watts.
A 12-volt electric motor has 1000 watts input and 1 horsepower output. Maintaining the same efficiency, how much input power will a 24-volt , 1-horsepower electric motor require? (Note: 1 horsepower = 746 watts)
1000 watts.
How many amperes will a 28-volt generator be required to supply to a circuit containing five lamps in parallel, three of which have a resistance of 6 ohms each and two of which have a resistance of 5 ohms each?
25.23 amperes.
A 24-volt, 1-horsepower DC electric motor that is 80% efficient requires 932.5 watts. How much power will a 12-volt, 1-horsepower DC electric motor that is 75% efficient require? (Note: 1 horsepower = 746 watts)
994.6 watts.
The potential difference between two conductors which are insulated from each other is measured in…
volts.
Which effect does not apply to the movement of electrons flowing in a conductor?
Static energy.
a 24-volt source is required to furnish 48 watts to a parallel circuit consisting of four resistors of equal value. What is the voltage drop across each resistor?
24 volts.
When calculating power in a reactive or inductive AC circuit, the true power is…
less than the apparent power.
How much power is being furnished to the circuit?
2645 watts.
What is the impedance of an AC-series circuit consisting of an inductor with a reactance of 10 ohms, a capacitor with a reactance of 4 ohms, and a resistor with a resistance of 8 ohms?
10 ohms.
(Refer to figure 6) If resistor R5 is disconnected at the junction of R4 and R3 as shown, what will the ohmmeter read?
3 ohms.
If resistor R3 is disconnected at terminal D, what will the ohmmeter read?
Infinite resistance.
With an ohmmeter connected into the circuit as shown, what will the ohmmeter read?
10 ohms.
How many instruments (voltmeters and ammeters) are installed correctly?
Two.
The correct way to connect a test voltmeter in a circuit is…
in parallel with a unit.
What will a voltmeter read if properly connected across a closed switch in a circuit with electrical power on?
Zero voltage.
What does the letter Q symbolize when measuring electrical charge?
Coulomb.
Which term means 0.001 ampere?
Milliampere.
A cabin entry light of 10 watts and a dome light of 20 watts are connected in parallel to a 30-volt source. If the voltage across the 10-watt light is measured, it will be…
equal to the voltage across the 20-watt light.
A 14-ohm resistor is to be installed in a series circuit carrying 0.05 ampere. How much power will the resister be required to dissipate?
At least 35 milliwatts.
0.002 kV equals…
2.0 volts.
What is the measured voltage of the series-parallel circuit between terminals A and B?
3.0 volts.
A 24-volt source is required to furnish 48 watts to a parallel circuit consisting of two resistors of equal value. What is the value of each resistor?
24 ohms.
Which requires the most electrical power?
A 1/5 horsepower, 24-volt motor which is 75 percent efficient.
What unit is used to express electrical power?
Watt.
What is the basic unit of electrical quantity?
Coulomb.
What is the operating resistance of a 30-watt light bulb designed for a 28-volt system?
26 ohms.
When referencing resistance in a parallel DC circuit, which of the following statements is true?
The total current is equal to the sum of the currents through the individual branches of the circuit.
Which of the following is commonly used as a rectifier in electrical circuits?
Diodes.
Diodes are used in electrical power supply circuits primarily as…
rectifiers.
Transfer of electrical energy from one circuit to another without the aid of electrical connections…
is called induction.
If three resistors of 3 ohms, 5 ohms, and 22 ohms are connected in series in a 28-volt circuit, how much current will flow through the 3-ohm resistor?
0.93 ampere.
A circuit has an applied voltage of 30 volts and a load consisting of a 10-ohm resistor in series with a 20-ohm resistor. What is the voltage drop across the 10-ohm resistor?
10 volts.
Find the total current flowing in the wire between points C and D.
3.0 amperes.
Find the voltage drop across the 8-ohm resistor.
24 volts.
In a parallel circuit with four 6-ohm resistors across a 24-volt battery, what is the total voltage across resistor-three (VR3) in the circuit?
24 volts.
If each cell, connected in series, equals 2 volts, how would a 12-cell lead acid battery be rated?
24 volts.
Find the total resistance of the circuit.
21.2 ohms.
Which is correct in reference to electrical resistance?
If one of the three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will become greater.
What happens to the current in a voltage step-up transformer with a ratio of 1 to 4.
The current is stepped down by a 1 to 4 ratio.
Determine the total current flow in the circuit.
1.4 amperes.
In a parallel circuit with three 6-ohm resistors across a 12-volt battery, what is the total current value in the circuit?
6 amps.
The total resistance of the circuit is…
17 ohms.
Which of these will cause the resistance of a conductor to decrease?
Decrease the length or increase the cross-sectional area.
Through which material will magnetic lines of force pass the most readily?
Iron.
A 48-volt source is required to furnish 192 watts to a parallel circuit consisting of three resistors of equal value. What is the value of each resistor?
36 ohms.
Which is correct concerning a parallel circuit?
Total resistance will be smaller than the smallest resistor.
The voltage drop in a circuit of known resistance is dependent on…
the amperage of the circuit.
A thermal switch, or thermal protector, as used in an electric motor, is designed to…
open the circuit in order to allow cooling of the motor.
With the landing gear retracted, the red indicator light will not come on if an open occurs in wire…
19.
Wire 7 is used to…
close the PUSH-TO-TEST circuit.
When the landing gear is down, the green light will not come on if an open occurs in wire…
6.
What will be the effect if the PCO relay fails to operate when the left-hand tank is selected?
The fuel pressure crossfeed valve open light will not illuminate.
The TCO relay will operate if 24-volts DC is applied to the bus and the fuel tank selector is in the…
crossfeed position.
With power to the bus and the fuel selector switched to the right-hand tank, how many relays in the system are operating?
Three.
When electrical power is applied to the bus, which relays are energized?
PCC and TCC.
(Refer to figure 16) Energize the circuit with the fuel tank selector switch selected to the left-hand position. Using the schematic, identify the switches that will change position.
5, 6, 11, 12, 13, 15, and 16.
Which of the components is a potentiometer?
3.
The electrical symbol represented at number 5 is a variable…
capacitor.
When the landing gear is up and the throttles are retarded, the warning horn will not sound if an open occurs in wire…
4.
The control valve switch must be placed in the neutral position when the landing gear is down to…
prevent the warning horn from sounding when the throttles are closed.
Under which condition will a ground be provided for the warning horn through both gear switches when the throttles are closed?
Left gear up and right gear down.
When the throttles are retarded with only the right gear down, the warning horn will not sound if an open occurs in wire…
5.
When the landing gears are up and the throttles are retarded, the warning horn will not sound if an open occurs in wire…
6.
When referring to an electrical circuit diagram, what point is considered to be at zero voltage?
The ground reference.
What is the purpose of the ground symbol used in electrical circuit diagrams?
To show that there is a return path for the current between the source of electrical energy and the load.
Troubleshooting an open circuit with a voltmeter as shown in this circuit will…
permit the battery voltage to appear on the voltmeter.
What symbol represents a variable resistor?
2.
In a P-N-P transistor application, the solid-state device is turned on when the…
base is negative with respect to the emitter.
In an N-P-N transistor application, the solid-state device is turned on when the…
base is positive with respect to the emitter.
Typical application for zener diodes is as…
voltage regulators.
Which illustration is correct concerning bias application and current (positive charge) flow?
1.
Forward biasing of a solid-state device will cause the device to…
conduct.
If an open occurs at R1, the light…
cannot be turned off.
If R2 sticks in the up position, the light will…
be on full bright.
Which statement concerning the depicted logic gate is true?
Any input being 1 will produce a 1 output.
In a functional and operating circuit, the depicted logic gate’s output will be 0…
when one or more inputs are 0.
Which of the logic gate output conditions is correct with respect to the given inputs?
2.
Which of the following logic gates will provide an active high out only when all inputs are different?
XOR.
A lead-acid battery with 12 cells connected in series (no-load voltage = 2.1 volts per cell) furnishes 10 amperes to a load of 2-ohms resistance. The internal resistance of the battery in this instance is…
0.52 ohm.
If electrolyte from a lead-acid battery is spilled in the battery compartment, which procedure should be followed?
Apply sodium bicarbonate solution to the affected area followed by a water rinse.
Which statement regarding the hydrometer reading of a lead-acid storage battery electrolyte is true?
The hydrometer reading does not require a temperature correction if the electrolyte temperature is 80 degrees Fahrenheit.
A fully charged lead-acid battery will not freeze until extremely low temperatures are reached because…
most of the acid is in the solution.
What determines the amount of current which will flow through a battery while it is being charged by a constant voltage source?
The state-of-charge of the battery.
1 and 2.
The method used to rapidly charge a nickel-cadmium battery utilizes…
constant voltage and varying current.
The purpose of providing a space underneath the plates in a lead acid batter’s cell container is to…
prevent sediment buildup from contacting the plates and causing a short circuit.
Which condition is an indication of improperly torqued cell link connections of a nickel-cadmium battery?
Heat or burn marks on the hardware.
The presence of any small amount of potassium carbonate deposits on the top of nickel-cadmium battery cells in service is an indication of…
normal operation.
What is the likely result, if any, of servicing and charging nickel-cadmium and lead-acid batteries together in the same service area?
Contamination of both types of batteries would occur.
Which of the following describes the operating principle in a nickel-cadmium battery installed in an aircraft?
To completely charge a nickel-cadmium battery, some gassing must take place; thus, some water will be used.
The electrolyte of a nickel-cadmium battery is the lowest when the battery is…
in a discharged condition.
The electrolyte of a nickel-cadmium battery is highest when the battery is…
in a fully charged condition.
The end-of-charge voltage of a 19-cell nickel-cadmium battery, measured while still on charge,…
depends upon its temperature and the method used for charging.
During discharge, nickel-cadmium batteries will show a lower liquid level than when at full charge because…
the electrolyte becomes absorbed into the plates.
How can the state-of-charge of a nickel-cadmium battery be determined?
By a measured discharge.
What may result if water is added to a nickel-cadmium battery when it is not fully charged?
Excessive spewing is likely to occur during the charging cycle.
In nickel-cadmium batteries, a rise in cell temperature…
causes a decrease in internal resistance.
Which of the following best describes the contributing factors to thermal runaway in nickel-cadmium battery installed in an aircraft?
Low internal resistance intensified by high cell temperatures and a high current discharge/charge rate in a constant potential (voltage) charging system.
When a charging current is applied to a nickel cadmium battery, the cells emit gas…
toward the end of the charging cycle.
