MOD 1 Flashcards
Matter can be found in what form
Solid, liquid, and gas
A substance that can not be reduced to a simpler substance by chemical means is called
Element
A molecule is the smallest possible particle that retains the characteristics of which of the following substances?
Compound
An atom is the smallest possible particle that retains the characteristics of what?
An element
What subatomic particle has a negative charge and a small mass?
Electron
What subatomic particle has a positive charge and a large mass
Proton
What subatomic particle has no charge
Neutron
When light is represented as a tiny packet of energy what are these packets of energy called?
Photons
If light energy collides with an orbiting electron what happens to the electron?
The electron will jump to an orbit further from the nucleus
After an electon jumps to an orbit fruther from the nucleus the electron will return to the condition it had before being acted upon by the light. When the electron returns to this condition, what occurs?
Light energy is emitted
The number of electrons in the outermost shell of an atom determines which of the following characteristics of the atom?
Valence
When an atom gains or loses an electron what term applies?
Ionized
What is the main difference between conductors, semiconductors, and insulators?
The number of free electrons
A substance with an excess of electrons is considered to be in what electrical state?
Negative
Easiest way to accumulate a static electric charge
Friction between two insulators
An atom that contains 6 protons and 5 electrons has what electrical charge
Positive
How do “like” and “unlike” charges react to ine another?
Unlike charges attract each other, like charges repel each other
What are the terms applied to the space between and around charged bodies in which their influence is felt?
Electric field of force, electrostatic field, dielectric field
Electrostatic linea of force are drawn in which of the following manners
Entering negative charge leaving positive charge
Which of the following devices use magnetism?
High-fidelity speakers
Magnetism materials have what qualities
They are attracted by magnets and can be magnetized
Ferromagnetic materials have which of the following qualities
They are relatively easy to magnetize
A material with low reluctance and high permeability such as iron or soft steel is used to make what type of magnet
Temporary
The abolity of a material to retain magnetism is called
Retentivity
The law of magnetic poles states which of the following relationships
Like poles repel, unlike poles attract
The north indicating pole of a compass needle is attracted to which of the following poles of the earth
The magnetic north pole
Webers theory of magnetism assumes that magnetic materia is composed of
Tiny molecular magnets
According to the domain theory, if an atom with 26 electrons has 20 electrons spinning counterclockwise the atom is considered to be
Magnetized
If a glass playe is places over a magnet and the iron fillings are sprinkled over the glass, a pattern will be visible. What does this pattern indicate?
The magnetic field
An imaginary line used to illustrate a magnetic effect is known as a
Magnetic line of force
Do magnetic lines of force ever cross
No
A magnetic shield or screen used to protect a delicate instrument should be made of what material
Soft iron
Bar magnets should be stored in which of the following manners
In pairs with north and south pole together
What is the term applied to the ability to do work
Energy
An object in motion has what kind of energy
Kinetic
A book sitting on a shelf has what kind of energy
Potential
What term applies to the difference of potential between two bodies
Voltage or electromotive force
What is 2.1kV converted
2100V
What are different ways to write 250micro volts
.25mV
.00025V
250x10^-6 V
What is the general term that describes a device which aupplies voltage
A voltage source
In addition to friction magnetism and chemical action what method can be used to produce voltage
Pressure, light, heat
What method of voltage does a radio receivers oscillator use
Pressure
What method of voltage does a thermocouple use
Heat
What method of voltage does an auto battery use
Chemical action
What method of voltage does a auto generator use
Magnetism
What method of voltage does a flashlight cell use
Chemical action
Current in an electric circuit is caused by what
Electrons moving from negative to positive
When directed drift takes place what speed
186,000miles per second
If voltage in a circuit increases what happens to current
Increases
What ampere is equal to 100mA
.10 ampere
What symbol is used to represent ohm
♎️
If low weight is the major factor what material should be used as a conductor
Aluminum
What material is most widely used as a conductor in electrical equipment
Copper
Resistance of a conductor will increase with which of the following changes to the cross-sectiknal area and length of the conductor
Cross sectional area decreased length increased
A material whose resistance decreases as the temperature increases has what temp coefficient
Negative
A material whose resistance remains constant as the temp increases has what temp coefficient
Zero
What is not a unit of conductance
Ohm
Resistance bears which if any relationship to conductance
Reciprocal
What schematic symbol represents a resisitor
Squiggle line
How is the abolity of a resistor to dissipate heat indicated
Wattage rating
Carbon resistors have which of the following disadvantages
Resistance value changes with age
What resistor overcomes rhe disadvantages of carbon
Wirewound resistors
What total number of connections does a rheostat have
2
What total number of connections does a potentiometer have
3
What type of variable resisitor is used to control a large amount of current
Rheostat
A carbon resistor color coded orange orange orange has what resistance value
33 kilo ohms
What are the allowable limits of ohmic value in a resistor color coded blue green yellow gold
682.5 killo ohms to 617.5 k ohms
What fifth color band on a resistor is least chance of failure
Yellow
What is the purpose of an electrical cell?
Convert chemical energy to electrical energy
What are the three basics parts of an electrical cell?
Electrodes, electrolyte, container
Describe electrolyte
Solution acting upon the electrode
Describe container
Mounting for the electrode
Describe anode
Positive electrode
Describe cathode
Negative electrode
What term is given to the process that takes place inside a cell?
Electrochemical action
With respect to recharging a primary or secondary cell, of the following statements, which one is correct?
The secondary cell can be recharged by passing current through it in the proper direction
What determines the amount of current that a cell can deliver to the external circuit?
The internal resistance of the cell only
What causes negative ions to be attracted to the cathode of a primary cell while the cell is discharging?
A positive charge causes by a loss of electrons
What causes hydrogen to be attracted to the anode of a primary cell when the cell is discharging?
A negative charge caused by an excess of electrons
Which actions will lower internal resistance of a cell
Increasing the space between electrodes (ask Garcia)
What causes the cathode to be “eaten away” in the primary cell while the cell is discharging
The material of the cathode combines with the negative ions to form a new substance
The primary cell is completely discharged when which of the following conditions exist?
The cathode is completely eaten away, the active ingredient in the electrolyte is used up, the voltage of the cell is reduced to zero
In a zinc-carbon primary cell, what is the function of the carbon electrode
To supply a return path for current
The lead-acid cell is an example of which of the following types of cells?
The secondary cell
In a full charged lead-acid cell, what is the composition of the anode, cathode, and electrolyte respectively
Lead peroxide, sponge lead, sulfuric acid, and water
Which of the following actions will recharge a secondary cell?
Connecting the negative terminal of a voltage source to the cathode of the cell and the positive terminal of the voltage source to the anode cell
When the lead-acid cell is discharging what are the chemical actions
Sulfuric cause decreasing, sponge lead decreasing, lead peroxide decreasing, lead sulfate increasing
When the lead-acid cell is charging what are the chemical actions
Sulfuric cause increasing, sponge lead increasing, lead peroxide increasing, lead sulfate decreasing
When all the lead sulfate in a lead acid cell is converted to sulfuric acid, lead peroxide and sponge lead what is the condition of the cell
Fully charged
Polarization has what effects on an electrical cell
Increases internal resistance, thereby decreasing the output voltage
Which of the following methods is used to control polarization in a cell
Venting the cell
Which of the following is caused by local action in a cell
Shelf life is reduced
In a dry cell, what is the consistency of the electrolyte
Paste
What serves as the cathode in a Common type of dry cell
Zinc container
How should the dry cell be stored to obtain max shelf life
In a Refrigerated space
The blotting paper in a dry cell serves what purpose
Separates the paste from the zinc, permits the electrolyte from the paste to filter through to the zinc slowly
Of the following characteristics, which one describes the mercury cell
It has a very stable output voltage
What is the shorting of a cell
Connecting the anode and cathode together without a load
What are the advantages of using a manganese-dioxide-alkaline-zinc cell over the zinc-carbon cell
Better voltage stability
Longer storage life
Operates over a wide temperature range
What is the common name for manganese-dioxide-alkaline-zinc cell
Alkaline cell
What factors should be considered when selecting a primary cell as a power source
Power requirement
Of the following types of cells, which one is a primary cell
Lithium organic
What are the differences in the construction of a NICAD cell as compared to a lead-acid cell
The electrolyte used the material of the anode and the material of the cathode
What is the most common use of a silver zinc cell?
Emergency equipment batteries
In addition to the nickel-cadmium and silver-zinc cells, which of the following cells uses potassium hydroxide as the active ingredient in the electrolyte
Silver-cadium
What is the minimum number of cells necessary to form a battery
One
What is the first step in performing maintenance on a secondary-cell battery
Check the technical manual for information on the specific type of battery
When a hydrometer is used to check the specific gravity of the electrolyte in a battery to what level should the electrolyte be drawn?
Enough so the float will rise without entering the suction bulb
To flush a hydrometer, which of the following liquids should be used
Fresh water
If the electrolyte level in a battery is low, what should be added to the electrolyte to bring it to the proper level
Distilled water
What safety precautions for batteries are not used
Terminals should be electrically connected together
If electrolyte comes in contact with the skin, what first aid treatment should be given immediately to the affected area
Flush with fresh water
A battery with a capacity of 600 ampere-hours should provide 3 amperes for a max of how many hours
200
A battery is rated according to a 20hr rate of discharge at 300 ampere hours. What is the max current that will allow the battery to deliver its rated capacity
15 amperes
What types of routine charges follow the name plate data in restoring a battery to its charged condition during the ordinary cycle of operation
Normal
If violent gassing occurs during the charging of a battery, which of the following actions should be taken
Decrease charging rate
If a battery is being charged at the proper rate which if any of the following types of gassing should occur
Steady gassing.
Initial charge
Used after electrolyte is added to a dry-shipped battery
Equalizing charge
Used periodically as part of a Maintenance routine
Floating charge
Used to keep a battery at full charge while the battery is idle
Fast charge
Used in emergency only
