Chapter 12 Basic Electricity
The speed of electron movement is considered to be____ miles per second. This is the same as the speed of____
186,000, Light
A series DC aircraft electrical circuit has a 12 volt battery, a 10 ohm resistor, and a 2 ohm resistor. What is the current flow in this circuit?
1
What is the resistance of these two composition resistors? brown - black - green - silver ____ red - red - red - no color ____
1,000,000 +- 10% 2200 +- 20%
How many watts of electrical power are needed to lift a 12,000-pound aircraft three feet in one minute? ____ horsepower is needed (two decimals) ____ watts of electrical power (one decimal)
1.09 813.8
The specific gravity of a fully charged lead-acid battery is approximately
1.275 - 1.3
What is the specific gravity of the electrolyte for a fully charged lead acid battery?
1.275-1.3
Divide and express your answer in scientific notion: (round to 2 decimals where necessary) 326,000,000 ÷ 1,900,000 = 365,000 ÷ 0.025 = 5,400 ÷ 18 =
1.72*10^2 1.46*10^7 3*10^2
Kirchoff's voltage law means that if I have a 12v battery in a circuit the loads in the circuit will use a total of ____ volts
12 (all of them)
Write the following numbers using metric prefixes: 126,000,000 ohms = ____ megaohms 0.002 amp = ____ milliamps 156,000 volts = ____ kilovolts 0.000000000002 farads = ____ picofarads 115,900,000 hertz = ____ megahertz 326,000 meters = ____ kilometers
126 2 156 2 115.9 326
A parallel DC aircraft electrical circuit has a 24 volt battery, a 2 ohm resistor, and a 16 ohm resistor. What is the current flow in this circuit?
13.48
How much current is required for a 12-volt DC electric motor to produce 1/4 horsepower if we assume that there are no losses in the system? 1/4 horsepower = ____ watts (round 1 decimal) In a 12-volt motor this will require ____ amps (round 1 decimal)
186.5 15.5
the first band on a resistor designates what?
1st number
A DPDT switch will control ____ circuits, and it has either ____ or 3 positions.
2 2 3
When a five-ohm resistance is placed in a 20-volt circuit, how much current will flow?
4 amps
If three amps of current are flowing in a 12-volt circuit, how much resistance is present?
4 ohms
Multiply and express your answer in scientific notion: 325,000,000 * 1,500,000 = 0.000002 * 45 = 750 * 0.25 =
4.875*10^14 9*10^-5 1.875*10^2
What is the total power and total current for a 12-volt aircraft system with the following equipment installed: (parallel) a. Navigation lights, 3 lights at 20 watts each = b. Radio 1, 60 watts = c. Radio 2, 30 watts = d. Interior lights, 30 watts = Total power = Total current =
5 amps 5 amps 2.5 amps 2.5 amps 180 watts 15 amps
What would the watts of power be for a DC aircraft flap circuit that had a 10 ohm resistor, a 12 ohm resistor, a 3 ohm resistor in series with a 12 volt battery?
5.76
How many cells does a 12V lead acid battery have if the cells are connected in series?
6 cells
What is the resistance of these two composition resistors? violet - gray - yellow - silver blue - green - white - gold yellow - black - gold - no color
780,000 +-10% 65,000,000,000 +-5% 4.0 +- 20%
A series DC aircraft electrical circuit contains a 3 ohm resistor, a 5 ohm resistor, and carries 10 amps. What is the voltage in the circuit?
80
Current is defined as ____ and is represented by the letter ____. It is measured in____
A flow of electric charge I Amperes
Conductor is defined as ____ and has ____ valence electrons
A substance in which electron flow is carried 1-4
Insulator is defined as ____ and has ____ valence electrons
A substance in which electron flow is not supported 5-8
Static dischargers on an aircraft control surface provide sharp points from which a static charge can be dissipated from the control surface into the
Air
Power is defined as ____ and is represented by the letter ____. it is measured in ____
Amount of work done in a circuit P Watts
Current is measured in what unit?
Amperage
When one coulomb of electrons flows past a point in one second, there is a current flow of one ____
Ampere
What remains constant in a series circuit
Amps
What is the smallest particle of any element?
Atom
Sources= Chemical: Thermal: Pressure: Light: Magnetism:
Battery thermocouple pizoelectric solar panel Motor
If water is added to any cell of a nickel-cadmium battery, the amount and location of the cell should be recorded in the battery service record
Battery service record
Flexible metal braids called _____ straps connect the control surfaces to the aircraft structure to prevent the buildup of static charges.
Bonding
What is used to statically balance an aircraft structure to the same electrical potential?
Bonding straps
What is used to neutralize the electrolyte from a NiCad battery?
Boric acid and vinegar
What is a battery?
Chemical energy converted into electrical energy.
A battery is a device which changes ____ energy into ____ energy
Chemical, electrical
Using a soft iron core in an electromagnet increases its strength because it ____ the lines of flux.
Concentrates
Materials that have less than 4 valence electrons are known as what?
Conductor
Electromagnetic induction is when electricity is produced by moving a ____ through a ____
Conductor, magnetic field
Materials which permit the flow of electrons are referred to as
Conductors
The ____ is the basic unit of electrical quantity and is equal to 6.28 billion, billion electrons.
Coulomb
The constant _____ charging method is the most effective method for charging aircraft batteries.
Current
Ohm's Law states that
E (voltage) = I (Amps) x R (ohms)
What is EMF?
Electromotive force
There are two types of electromagnets used in practical applications, those having ____ cores and those having ____ cores (alphabetical)
Fixed, Moveable
Current is defined as?
Flow of electrons
Two types of circuit protective devices would include:
Fuse & circuit breaker
As a nickel-cadmium battery nears completion of its charge, ____ of the cells will occur
Gassing
One____ represents a magnetic flux density of one maxwell per square centimeter.
Gauss
Magnetic lines of flux with soft iron? (go through or go around)
Go through (permeability)
The electrolyte level of a nickel-cadmium battery is ____ immediately after the battery charge is completed.
Highest
What letter is used to designate current?
I or A
Materials that have 5 or more valence electrons are known as what?
Insulator
a charged atom is known as a(n)
Ion
The most commonly used storage battery in light aircraft is the ____ battery.
Lead acid
When a lead-acid battery is discharged, the active material on both positive and negative plates is converted to ____
Lead sulfate
When electrons flow in a conductor, they cause a(n)_____ (two words) to surround the conductor.
Magnetic field
What meter is used to test insulation?
Mega Meter
What meter is used to test bonding straps?
Mili Meter
Actual current flow is from
Negative to positive
Electron flow is considered to be from the ____ terminal of the battery (or other current source) through the circuit and return to the ____ terminal of the battery.
Negative, Positive
What is "deep cycling"?
NiCad battery set to zero volts. short cells and recharge
Both the positive and the negative plates of a nickel-cadmium cell are made of powered nickel plaque, fused to a nickel screen. a. the positive plates are impregnated with ____ Hydroxide b. the negative plates are impregnated with ____ hydroxide
Nickel, cadmium
Magnetic field flow from ____ to ____
North to south
The lines of magnetic flux are considered to leave the ____ pole of a magnet and enter at the ____ pole.
North, South
The strength of an electromagnet is determined by the ____ and by the ____ flowing through it.
Number of turns, Amount of current
The ____ is the standard unit of electrical resistance, or opposition to current flow.
Ohm
What type of meter supplies its own power?
Ohmmeter
Resistance is measured in what?
Ohms
What meter uses its own power?
Ommeter
When two magnets are brought together, which poles will attract each other?
Opposites attract, negative to positive and positive to negative.
Resistance is defined as what?
Opposition to current flow
What are valence electrons?
Outer shel
What are the two formulas used to represent Ohm's law
P=IxE E=IxR
A ohmmeter is hooked up in ____ to a circuit, power is ____ , polarity ____ matter.
Parallel off no
A voltmeter is hooked up in____ to a circuit, power is ____, polarity ____ matter.
Parallel on yes
A ohmmeter is connected into a circuit how?
Parallel, power off, isolate the unit
The production of electrical signals through the use of mechanical strain is referred to as :
Piezoelectrics
What collects on the top of a NiCad battery____
Potassium Carbonate
The white powder that forms on the top of a nickel-cadmium battery that has been in service is____
Potassium carbonate
A ____ may be used as a voltage divider.
Potentiometer
A variable resistor having three terminals is called a ____
Potentiometer
resistance is designated by what letter?
R
____ is the opposition to the flow of magnetic force.
Reluctance
____ magnetism is the magnetism remaining in a material after the magnetizing force has been removed.
Residual
Electronic symbols are commonly found on :
Schematics
If there is only one path for electrons to flow, the circuit is called a ____ circuit
Series
A ammeter is connected into a circuit how?
Series and power on polarity matters
A ammeter is hooked up in ____ to a circuit, power is ____, polarity ____
Series, on, yes
Match the switches : SPST DPDT SPDT DPST
Single pull single throw double pull double throw single pull double throw double pull single throw
Static electricity will distribute evenly on ____ surfaces, but will collect on ____ surfaces
Smooth, Rough
Spilled electrolyte from a lead-acid battery may be neutralized using a solution of
Sodium Bicarbonate and water
What is used to neutralize the electrolyte from a lead acid battery?
Sodium bicarbonate/ baking soda
The sum of all the voltage drops in a series circuit is equal to the ____ ____
Source Voltage
What happens to the electrolyte in a lead acid battery during discharge?
Specific gravity decreases, and it is more susceptible to freezing
The active material on the negative plate of a fully charged lead-acid battery is ____
Spongey Lead
When an aircraft is fueled, it should be electrically connected to the fuel truck and to the ground to prevent a spark caused by an accumulation of ___ electricity on the aircraft surface.
Static
Excessive static charges can be eliminated on an aircraft in flight by the use of?
Static wave
Match the following regarding static discharge and balancing. Used to discharge static electricity on aircraft ____ Used to statically balance a landing gear door ____
Static wick, bonding strap
Magnetism around a conductor _____ when the applied current is stopped.
Stops
The electrolyte of a lead-acid battery is made up of
Sulfuric acid and water
Resistance in a series DC circuit is the ____ of all the resistors.
Sum
The total resistance in a series circuit is the ____ of the individual load resistances.
Sum
The ampere-hour capacity of a lead-acid battery is determined by:
Temperature quantity of electrolyte amount of active material plate surface area
Power is defined as what?
The amount of work being performed
What does the measured discharge test tell a mechanic?
The state of charge of a NiCad battery
The unit of electrical pressure is known as the ____
Volt
A nickel-cadmium battery battery can maintain a nearly constant ____ until it is almost totally discharged.
Voltage
What remains constant in a parallel circuit ?
Voltage
What is EMF measured in?
Volts
What letter is used to represent voltage (EMF) ?
Volts
What letter is used to designate power?
W or P
A resistor in an aircraft dome light circuit breaks loose and is damaged. The old resistor has a color code of red, brown, black. What is the rated resistance of this component to determine a replacement resistor?
Your Answer: red -2 brown -1 black -0 21ohms +-20%
Resistance is defined as ____ and is represented by the letter ____. it is measured in ____
a force opposing the flow of electrons R Ohms
Electromotive Force is defined as ____ and is represented by the letter ____ . It is measured in ____
as a difference in potential that tends to give rise to electron flow E Volts
A primary cell _____ be recharged
can not
Name five ways electrical energy may be generated (alphabetical)
chemical light magnetism pressure thermal
Name the three components needed to complete an electrical circuit.
conductor, load, source
A rheostat controls power by varying the _____ through a circuit
current
In a series circuit, the ____ is the same throughout the circuit
current
The capacity of a battery is its ability to produce a given amount of ____ for a specified time.
current
If the capacity of a nickel-cadmium battery is less than it should be, or if there is an indication that some of the cells are unbalanced, the battery should be ____
deep cycled
The specific gravity of the electrolyte in a nickel-cadmium battery ____ change as the state of charge of the battery changes
does not
What is it called when you move a conductor through magnetic lines of flux? (2 words)
electromagnetic induction
The magnetic properties of copper wire creates electromagnetism.
false
How is a lead acid battery measured?
hydrometer
What can damage a magnet?
impact & heat
A material is said to have a positive temperature coefficient of resistance if its resistance increases as its temperature _____
increases
Wire conductors ____ in resistance as temperature increases.
increases
What are megaohmeters usesd for? (2 words)
insulation check
Materials which oppose the movement of electrons are called
insulators
When using a multimeter, the circuit needs to be ____ when testing for resistance.
isolated and power off
The active material on the positive plate of a fully charged lead-acid battery is _____
lead peroxide
The five-minute discharge rate of a lead-acid battery gives ____ ampere-hours than the five-hour rate?
less
Resistance in a parallel DC circuit will always be ____ than the ____ resistor.
lower; lowest
One line of magnetic flux is called a ____
maxwell
During the service of a nickel-cadmium battery, the electrical leakage between the cells and the case should be checked using a _____
milliammeter
When removing a battery from an aircraft, you should remove the ____ lead first
negatiive
A body having an accumulation of electrons on its surface is said to have a ____ .
negative
An atom having more electrons than protons will carry a negative charge.
negative
the third band on a resistor designates what?
number of zeros
During the installation of a battery into an aircraft, when should the negative terminal be connected?
the very last point of service/after the positive lead
the fourth band on a resistor designates what?
tolerance
The ____ dissipated in a series circuit is equal to the sum of the power dissipated in each of the individual load resistances.
total power
High charging currents in nickel-cadmium batteries may cause a breakdown of the cellophane-like cell separator material, resulting in a condition known as ____ or ____
vicious cycling, thermal runaway
A potentiometer controls power by varying the ____ through a circuit
voltage
Electromotive Force is another way of describing ____. (unit of measure)
voltage
The generating system in an aircraft utilizes the constant ____ method to charge a battery.
voltage
Each unit of electrical measurement may be expressed using a single letter. What letters are used for the following expressions? Voltage= current= resistance= power=
voltage= E current= I resistance= R power= P
Electrical power is expressed in
watts
Power is measured in what?
watts
The open circuit voltage of a lead-acid battery is approximately ____ volts
2.1
A 60-watt light bulb installed in a 24-volt circuit will cause how much current to flow?
2.5 amps
the second band on a resistor designates what?
2nd number
What is the voltage required, to push 3 amps through 8 ohms of resistance?
3 amps x 800 ohms
Static electricity is the build up of an electrical charge on an aircraft or other surface.
True
An aircraft technician wishes to install an additional landing light onto a light aircraft. What are the minimum components required for this installation to function safely? (what materials are needed to make a complete safe circuit)
battery and wires
If there is an interruption, or break, in an electrical circuit, it is said to be ____
open
A resistor will ____ current in a circuit and can be fixed or variable.
oppose
What does O.L. indicate when displayed on a digital ohmmeter?
over limit or open line
A voltmeter is connected into a circuit how?
parallel and power on polarity matters
The ease with which lines of magnetic flux can pass through a material is known as a material's
permeability
Reversing the current in an electromagnet also reverses the ____.
polarity
An atom having fewer electrons than protons will carry a positive charge.
positive
When installing a battery in an aircraft, you should connect the ____ lead first
positive
The conventional theory says electricity flows from
positive to negative
The electrolyte for a nickel-cadmium battery is ____
potassium hydroxide and water
The basic parts of an atom are : (one word) (positive charge) ____ (neutral charge) ____ (negative charge) ____
proton neutron electron
Like charges ____ each other. Unlike charges ____ each other.
repel, attract
____ is the ability of a material to retain magnetism after a magnetizing force is removed.
retentivity
A variable resistor having two terminals is called a ____
rheostat
A glass tubular fuse that uses a small spring to pull the fusible link apart is called a
slow blow fuse
An electromagnetic switch having a movable core is called a
solenoid
What is the largest concern during fueling?
static build up
Nickel-cadmium battery installations are required to have ____ monitoring equipment.
temperature
The resistance of a conductor is affected by what three factors?
temperature, physical characteristics, dimensions
Coulomb is defined as ____ and is represented by the letter ____
the SI unit of electric charge, equal to the quantity of electricity conveyed in one second by a current of one ampere; 6.28 billion billion electrons. Q
