ELECTRICITY FUNDAMENTALS

Which of the following best describes the operating principle in a nickel-cadmium battery installed in an aircraft?

• At full charge, the electrolyte will be at its lowest level and should be filled.

• When positive plates slowly give up oxygen, which is regained by the negative plates, the battery is charging.

• To completely charge a nickel-cadmium battery, some gassing must take place; thus, some water will be used.

• To completely charge a nickel-cadmium battery, some gassing must take place; thus, some water will be used.

 If electrolyte from a lead-acid battery is spilled in the battery compartment, which procedure should be followed? 

• Apply boric acid solution to the affected area followed by a water rinse. 

• Rinse the affected area thoroughly with clean water. 

• Apply sodium bicarbonate solution to the affected area followed by a water rinse.

• Apply sodium bicarbonate solution to the affected area followed by a water rinse.

 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

• 5.0 ohms

• 2.52 ohms

• 0.52 ohm

What unit is used to express electrical power?

• Volt

• Watt

• Ampere

• Watt

Capacitors are sometimes used in dc circuits to

• Counteract inductive reactance at specific locations.

• Assist in stepping voltage and current up and/or down.

• Smooth out slight pulsations in current/voltage.

• Smooth out slight pulsations in current/voltage.

The electrolyte of a nickel cadmium battery is highest when the battery is

• In a discharged condition

• Under a no-load condition

• In fully charged condition

• In fully charged condition

A 12-volt electric motor has 1,000 watts input and 1 hp output. Maintaining the same efficiency, how much input power will a 24-volt, 1 hp electric motor require? (Note: 1 hp = 746 watts)

• 2,000 watts

• 1,000 watts

• 500 watts

• 1,000 watts

In an N-P-N transistor application, the solid state device is turned on when the

• Base is positive with respect to the emitter.

• Base is negative with respect to the emitter.

• Emitter is positive with respect to the base.

• Base is positive with respect to the emitter.

The correct way to connect a test voltmeter in a circuit is

• In parallel with a unit.

• Between the source voltage and the load.

• In series with a unit.

• In parallel with a unit.

Unless otherwise specified, any values given for current or voltage in an ac circuit are assumed to be

• Instantaneous values

• Effective values

• Maximum values

• Effective values

What factors strengthen a coil inductor?

• Limiting and separating the coils.

• Adding coils close together.

• Adding and separating the coils

• Adding coils close together.

hich of the following best describes the contributing factors to thermal runaway in a nickel-cadmium battery installed in an aircraft?

• Low internal resistance intensified by high cell temperatures and a high voltage discharge/charge rate in a constant current charging system.

• High internal resistance intensified by high cell temperatures and a high current discharge/charge rate in a constant potential (voltage) charging system.

• Low internal resistance intensified by high cell temperatures and a high current discharge/charge rate in a constant potential (voltage) charging system.

• Low internal resistance intensified by high cell temperatures and a high current discharge/charge rate in a constant potential (voltage) charging system.

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?

• 30 volts

• 20 volts

• 10 volts

• 10 volts

When inductors are connected in series in a circuit, the total inductance is (where the magnetic fields of each inductor do not affect the others). (Note: L(T) = L(1) + L(2) + L(3)...)

• Equal to the inductance of the highest rated inductor.

• Equal to the sum of the individual inductances.

• Less than the inductance of the lowest rated inductor.

• Equal to the sum of the individual inductances.

When a charging current is applied to a nickel-cadmium battery, the cells emit gas

• Especially if the electrolyte level is high.

• Throughout the charging cycle.

• Toward the end of the charging cycle.

• Toward the end of the charging cycle.

The voltage drop in a circuit of known resistance is dependent on

• The amperage of the circuit.

• The voltage of the circuit.

• Only the resistance of the conductor and does not change with a change in either voltage or amperage.

• The amperage of the circuit.

The electrolyte of a nickel-cadmium battery is the lowest when the battery is

• In a discharged condition.

• Under a heavy load condition.

• Being charged.

• In a discharged condition.

The amount of electricity a capacitor can store is directly proportional to the

• Plate area and is not affected by the distance between the plates.

• Distance between the plates and inversely proportional to the plate area.

• Plate area and inversely proportional to the distance between the plates.

• Plate area and inversely proportional to the distance between the plates.

A thermal switch, or thermal protector, as used in an electric motor, is designed to

• Reroute the circuit to ground.

• Close the integral fan circuit to allow cooling of the motor.

• Open the circuit in order to allow cooling of the motor.

• Open the circuit in order to allow cooling of the motor.

What does the letter Q symbolize when measuring electrical charge?

• Electron

• Farad

• Coulomb

• Coulomb

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-the-charge of the battery.

• The total plate area of the battery.

• The ampere-hour capacity of the battery.

• The state-of-the-charge of the battery.

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?

• 18 volts

• 6 volts

• 24 volts

• 24 volts

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.

• Excessive electrolyte dilution.

• No adverse effects since water may be added anytime.

• Excessive spewing is likely to occur during the charging cycle.

What is the opposition to the flow of the AC produced by a magnetic field with generated back voltage (EMF) called?

• Capacitive reactance

• Inductive reactance

• Mutual inductance

• Inductive reactance

In a parallel circuit with three 6-ohm resistors across a 12-volt battery, what is the total current (It) value in the circuit?

• 12 amps

• 2 amps

• 6 amps

• 6 amps

When different rated capacitors are connected in parallel in a circuit, the total capacitance is (Note: C(T) = C(1) + C(2) + C(3)...)

• Less than the capacitance of the lowest rated capacitor.

• Equal to the sum of all the capacitances.

• Equal to the capacitance of the highest rated capacitor.

• Equal to the sum of all the capacitances.

Which is correct in reference to electrical resistance?

• An electrical device that has a high resistance will use more power than one with a low resistance with the same applied voltage.

• Two electrical devices will have the same combined resistance if they are connected in series as they will have if connected in parallel. 

• If one of three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will become greater.

• If one of three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will become greater.

Through which material will magnetic lines of force pass the most readily?

• Iron

• Copper

• Aluminum

• Iron

Typical application for zener diodes is as

• Voltage regulators

• Half-wave rectifiers

• Full-wave rectifiers

• Voltage regulators

During discharge, nickel-cadmium batteries will show a lower liquid level than when at full charge because

• The electrolytes become absorbed into the plates.

• Current leakage from individual cells causes a rise in temperature.

• A chemical action causes the electrolyte to evaporate through the vents.

• The electrolytes become absorbed into the plates.

Convert farads to microfarads by

• Multiplying microfarads by 10 to the power of 6.

• Multiplying picofarads by 10 to the power of 6.

• Multiplying farads by 10 to the power of 6

• Multiplying farads by 10 to the power of 6

When referring to an electrical circuit diagram, what point is considered to be at zero voltage?

• The circuit breaker.

• The ground reference.

• The switch.

• The ground reference.

The purpose of providing a space underneath the plates in a lead acid battery's cell container is to

• Allow for convection flow of the electrolyte in order to provide for cooling of the plates.

• Prevent sediment buildup from contacting the plates and causing a short circuit.

• Ensure that the electrolyte quantity ratio to the number of plates and plate area is adequate.

• Prevent sediment buildup from contacting the plates and causing a short circuit.

The presence of any small amount of potassium carbonate deposits on the top of nickel-cadmium battery cells in service is an indication of

• Excessive gassing

• Plate sulfation

• Normal operation

• Normal operation

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.

• One-third of the input voltage.

• Half the voltage across the 20-watt light.

• Equal to the voltage across the 20-watt light.

Which of the following statements is/are generally true regarding the charging of several aircraft batteries together? 

1. Batteries of different voltages (but similar capacities) can be connected in series with each other across the charger, and charged using the constant current method. 

2. Batteries of different ampere-hour capacity and same voltage can be connected in parallel with each other across the charger, and charged using the constant voltage method. 

3. Batteries of the same voltage and same ampere-hour capacity must be connected in series with each other across the charger, and charged using the constant current method. 

• 2 and 3

• 1 and 2

• 3

• 1 and 2

Which effect does not apply to the movement of electrons flowing in a conductor?

• Thermal energy

• Static energy

• Magnetic energy

• Static energy

What is the total capacitance of a certain circuit containing three capacitors with capacitances of .25 microfarad, .03 microfarad, and .12 microfarad, respectively? (Note: C(T) = C(1) + C(2) + C(3))

• .04 pF

• .4 F

• .04 F

• .4 F

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?

• 6 volts

• 24 volts

• 12 volts

• 24 volts

When calculating power in a reactive or inductive ac circuit, the true power is

• More than the apparent power.

• Less than the apparent power in a reactive circuit and more than the apparent power in an inductive circuit.

• Less than the apparent power

• Less than the apparent power

Which term means .001 ampere?

• Microampere

• Milliamper

• Kiloampere

• Milliamper

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.

• The current is stepped up by a 1 to 4 ratio.

• The current does not change.

• The current is stepped down by a 1 to 4 ratio.

Which requires the most electrical power? (Note: 1 horsepower = 746 watts)

• A 24-volt anti-collision light circuit consisting of two light assemblies which require 3 amperes each during operation.

• A 1/5-horsepower, 24-volt motor which is 75 percent efficient.

• Four 30-watt lamps arranged in a 12-volt parallel circuit.

• A 1/5-horsepower, 24-volt motor which is 75 percent efficient.

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

• 9.3 amperes

• 1.05 amperes

• 0.93 ampere

The potential difference between two conductors which are insulated from each other is measured in

• Volts

• Amperes

• Coulombs

• Volts

What will a voltmeter read if properly connected across a closed switch in a circuit with electrical power on?

• System voltage.

• Zero voltage.

• Voltage drop in the component(s) the switch is connected to.

• Zero voltage.

In an ac circuit, the effective voltage is

• Equal to the maximum instantaneous voltage.

• Less than the maximum instantaneous voltage.

• Greater than the maximum instantaneous voltage.

• Less than the maximum instantaneous voltage.

Which of these will cause the resistance of a conductor to decrease?

• Decrease the length or increase the cross-sectional area.

• Increase the length or decrease the cross-sectional area.

• Decrease the length or the cross-sectional area.

• Decrease the length or increase the cross-sectional area.

002KV equals

• 20 volts

• .2 volt

• 2.0 volts

• 2.0 volts

What is the likely result of servicing and charging nickel-cadmium and lead acid batteries together in the same service area?

• Lowered amp-hour capacities, for both types of batteries.

• Contamination of both types of batteries.

• Reduced battery service life for both types of batteries.

• Contamination of both types of batteries.

Electrostatic fields are also known as

• Electrostatic fields

• Dielectric fields

• Static fields

• Dielectric fields

The term that describes the combined resistive forces in an ac circuit is

• Reactance

• Resistance

• Impedance

• Impedance

Which statement regarding the hydrometer reading of a lead-acid storage battery electrolyte is true?

• A specific gravity correction should be added to the hydrometer reading if the electrolyte temperature is below 59° F.

• The hydrometer reading does not require a temperature correction if the electrolyte temperature is 80° F.

• The hydrometer reading will give a true indication of the capacity of the battery regardless of the electrolyte temperature.

• The hydrometer reading does not require a temperature correction if the electrolyte temperature is 80° F.

If each cell, connected in series, equals 2 volts, how would a 12-cell lead acid battery be rated?

• 6 volts

• 24 volts

• 12 volts

• 24 volts

Convert farads to picofarads by:

• Multiplying microfarads by 10 to the power of -12

• Multiplying picofarads by 10 to the power of 12

• Multiplying farads by 10 to the power of 12

• Multiplying farads by 10 to the power of 12

What is the basic unit of electrical quantity?

• Electromotive Force

• Ampere

• Coulomb

• Coulomb

Which condition is an indication of improperly torqued cell link connections of a nickel-cadmium battery?

• Toxic and corrosive deposits of potassium carbonate crystals.

• Light spewing at the cell caps.

• Heat or burn marks on the hardware.

• Heat or burn marks on the hardware.

The opposition offered by a coil to the flow of alternating current is called (disregard resistance)

• Impedance

• Reluctance

• Inductive reactance

• Inductive reactance

A fully charged lead-acid battery will not freeze until extremely low temperatures are reached because

• Most of the acid is in the solution.

• The acid is in the plates, thereby increasing the specific gravity of the solution.

• Increased internal resistance generates sufficient heat to prevent freezing.

• Most of the acid is in the solution.

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? 

• 1.11 amperes

• 25.23 amperes

• 1 ampere

• 25.23 amperes

Which requires the most electrical power during operation? (Note: 1 hp = 746 watts)

• Two lights requiring 3 amperes each in a 24-volt parallel system.

• Four 30-watt lamps in a 12-volt parallel circuit.

• A 12-volt motor requiring 8 amperes.

• Two lights requiring 3 amperes each in a 24-volt parallel system.

An increase in which of the following factors will cause an increase in the inductive reactance of a circuit?

• Resistance and capacitive reactance

• Inductance and frequency

• Resistance and voltag

• Inductance and frequency

What is the total capacitance of a circuit containing three capacitors in parallel with capacitances of .02 microfarad, .05 microfarad, and .10 microfarad, respectively?

• 0.125 pF

• 0.0125 uF

• 0.170 uF

• 0.170 uF

Forward biasing of a solid state device will cause the device to

• Turn off

• Conduct via zener breakdown

• Conduct

• Conduct

When referencing resistance in a parallel DC circuit, which of the following statements is true?

• The current in amperes can be found by dividing the EMF in volts by the sum of the resistors in ohms.

• The current is equal in all portions of the circuit.

• The total current is equal to the sum of the currents through the individual branches of the circuit.

• The total current is equal to the sum of the currents through the individual branches of the circuit.

The basis for transformer operation in the use of alternating current is mutual

• Inductance

• Reactance

• Capacitance

• Inductance

In nickel-cadmium batteries, a rise in cell temperature

• Causes a decrease in internal resistance.

• Causes an increase in internal resistance.

• Increases cell voltage.

• Causes a decrease in internal resistance.

Which of the following logic gates will provide an active high out only when all inputs are different?

• XOR

• XNOR

• NAND

• XOR

Which is correct concerning a parallel circuit?

• Total resistance will be smaller than the smallest resistor.

• Total resistance will decrease when one of the resistances is removed.

• Total voltage drop is the same as the total resistance.

• Total resistance will be smaller than the smallest resistor.

What is the operating resistance of a 30-watt light bulb designed for a 28-volt system?

• 26 ohms

• 1.07 ohms

• 0.93 ohm

• 26 ohms

A 1-horsepower, 24-volt dc electric motor that is 80 percent efficient requires 932.5 watts. How much power will a 1-horsepower, 12-volt dc electric motor that is 75 percent efficient require?

(Note: 1 horsepower = 746 watts)

• 1,305.5 watts

• 994.6 watts

• 932.5 watts

• 994.6 watts

A 14-ohm resistor is to be installed in a series circuit carrying .05 ampere. How much power will the resistor be required to dissipate?

• At least .70 milliwatt

• Less than .035 watt

• At least 35 milliwatts

• At least 35 milliwatts

In a P-N-P transistor application, the solid state device is turned on when the

• Emitter is negative with respect to the base.

• Base is positive with respect to the emitter.

• Base is negative with respect to the emitter.

• Base is negative with respect to the emitter.

Transfer of electric energy from one circuit to another without the aid of electrical connections

• Is called capacitance.

• Is called induction.

• Can cause excessive arcing and heat, and as a result is practical for use only with low voltages/amperages.

• Is called induction.

Which of the following is commonly used as a rectifier in electrical circuits?

• Anodes

• Cathodes

• Diodes

• Diodes

How can the state-of-charge of a nickel-cadmium battery be determined?

• By a measured discharge.

• By measuring the specific gravity of the electrolyte.

• By the level of electrolyte.

• By a measured discharge.

The working voltage of a capacitor in an ac circuit should be

• Equal to the highest applied voltage.

• At least 20% greater than the highest applied voltage.

• At least 50% greater than the highest applied voltage.

• At least 50% greater than the highest applied voltage.

The method used to rapidly charge a nickel-cadmium battery utilizes

• Constant current and constant voltage

• Constant voltage and varying current

• Constant current and varying voltage

• Constant voltage and varying current

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.

• Must be 1.4 volts per cell.

• Must be 1.2 to 1.3 volts per cell.

• Depends upon its temperature and the method used for charging.

What is the purpose of the ground symbol used in electrical circuit diagrams?

• To show the source of electrical energy for the load.

• To show that there is a common bus for connection of the source of electrical energy to the load.

• To show that there is a return path for the current between the source of electrical energy and the load.

• To show that there is a return path for the current between the source of electrical energy and the load.