NCTI Installer Tech
100% SOLUTIONS
REVISED 2023//2024
Why do only the outer electrons leave their orbit shells? - ANSWER Only outer
electrons leave their orbit shells because electrons farthest from the nucleus are more
easily freed from their orbits due to a weaker electrostatic force.
Wh...
NCTI Installer Tech
100% SOLUTIONS
REVISED 2023//2024
Why do only the outer electrons leave their orbit shells? - ANSWER Only outer
electrons leave their orbit shells because electrons farthest from the nucleus are more
easily freed from their orbits due to a weaker electrostatic force.
What is required to have a balanced (or stable) atom? - ANSWER The number of
electrons must equal the number of protons in order to have a balanced atom.
List the capacity of each of the first four orbital shells of an atom. - ANSWER Shell: #1
= 2 electrons; #2 = 8 electrons; #3 = 18 electrons; and #4 = 32 electrons.
What is the maximum electron capacity of a valence shell? - ANSWER A valence shell
can hold a maximum of eight electrons.
Electrons in orbits nearest the nucleus contain _________ energy than those in more
distant orbits. - ANSWER Electrons in orbits nearest the nucleus contain less energy
than those in more distant orbits.
What will happen to a valence electron that has enough energy added to it? - ANSWER
A valence electron that has enough energy added to it will move away from its atom.
What major factor determines which category a particular element belongs? -
ANSWER The number of electrons in the valence shell determines the element
category.
How many valence electrons are there in a good conductor? - ANSWER A good
conductor has only one or two valence electrons.
,List gold, silver, and copper in the order of best conductivity. (List the best conductor
first.) - ANSWER #1 Silver; #2 Copper; #3 Gold
Why do metals that each have only one valence electron differ in their conductivity? -
ANSWER Metals that each have one valence electron differ in their conductivity
because of the way their atoms pack together into a solid structure.
Describe the two characteristics of an insulator. - ANSWER The two characteristics of
an insulator are as follows:
1. Its valence shell is almost filled and tends to be fairly stable.
2. It tries to finish filling its valence shell by capturing additional free electrons.
How many valence electrons are in a semiconductor? - ANSWER A semiconductor has
four valence electrons.
Name the two types of electron current flow. - ANSWER Random drift and directed flow
are the two types of electron current flow.
What causes electrons to be knocked loose and travel randomly from one atom to
another? - ANSWER The movement of atoms in materials that are conductors and the
agitation as they collide cause electrons to be knocked loose and travel randomly from
one atom to another.
What can force electrons to all move in the same direction? - ANSWER Applying a
negative charge to one end of the wire and a positive charge to the other can force
electrons to all move in the same direction. The electrons in the wire will travel toward
the positive charge as they are directed by the effects of the unlike charges.
What actually produces electric current? - ANSWER The transfer of energy from
valence electron to valence electron, as a result of applied charges, is what actually
produces electric current.
How does the speed of electric current compare to that of electron travel? - ANSWER
The effective speed of electric current (186,000 miles per second) is much faster than
the actual speed of electron travel (a few hundred miles per second).
How many electrons are in one coulomb? - ANSWER A coulomb is equal to 6.28 ×
1018 electrons.
What is the basic measurement unit of electron current? - ANSWER The ampere is the
basic measurement unit for electron current.
Define ampere in terms of coulombs. - ANSWER An ampere is equal to 1 coulomb
passing a given point during 1 second.
,Name the three terms that are used interchangeably to refer to the force that causes
current flow. - ANSWER Potential difference, electromotive force (emf), and voltageare
used interchangeably to refer to the force that causes current flow.
Define electromotive force (emf). - ANSWER Emf is the electrical force that motivates
electrons to move in a wire.
What does the term potential difference mean? - ANSWER Potential difference is the
algebraic difference between the electrical individual potentials of two points.
What is the potential difference between two negative charges of equal value? -
ANSWER The potential difference between two negative charges of equal value is zero.
There is no potential difference.
What is the unit used to indicate the strength or size of the potential difference? -
ANSWER The volt is the unit used to indicate the strength or size of the potential
difference.
Define a volt in terms of current and resistance. - ANSWER One volt is the amount of
force required to produce a current of 1 ampere through a resistance of 1 Ω.
What are three alternate ways to express 5 µV and 3 mA? - ANSWER 5 microvolts,
5/1,000,000 volt or 0.000005 volt, and 3 milliamperes, 3/1,000 ampere or 0.003 A.
What are two alternate ways to express 2 megavolts? - ANSWER 2 MV or 2 million
volts.
What are two alternate ways to express 4 kilovolts? - ANSWER 4 kV or 4,000 volts.
20 milliamperes is the same as ________. (Remember, 1 milliampere = 0.001 ampere.)
- ANSWER 0.02 amperes
The orbital shell that has a maximum electron capacity of 18 electrons is the
___________ shell. - ANSWER Third
A semiconductor material - ANSWER Has four valence electrons.
The major factor for determining whether a particular element is a conductor, a
semiconductor, or an insulator is - ANSWER The number of electrons in the valence
shell.
Elements that are called conductors - ANSWER Have very few valence electrons.
The term voltage normally refers to - ANSWER The measurement of the difference in
potential between two charges.
, The ampere - ANSWER Indicates how many coulombs pass a given point during 1
second.
Electric current is actually produced by - ANSWER The transfer of energy from valence
electron to valence electron as a result of applied charges.
What prevents the electrons that orbit an atom's nucleus at high speeds from breaking
away from the nucleus due to centrifugal force? - ANSWER The attraction between the
positive nucleus and the negative electron.
5 kilovolts is the same as - ANSWER 5 kV.
What would happen if you suspended magnetite by a string and allowed it to swing
freely? - ANSWER Magnetite will always align itself in a north and south direction when
you suspend it by a string and allow it to swing freely.
What do scientists believe causes magnetism? - ANSWER Scientists believe that
magnetism results from the spinning action of each electron on its own axis and orbiting
around its own nucleus.
Why are some materials magnetic and others not? - ANSWER An atom of magnetic
material has more electrons spinning in one direction than in the other; nonmagnetic
material has an equal number of electrons spinning in opposite directions.
Describe the pattern arrangement of the magnetic domains in nonmagnetized and
magnetized materials. - ANSWER The magnetic domains in a nonmagnetized material
arrange in a random pattern, which causes the effects to cancel, resulting in no
magnetic field. Those in a magnetized material align in the same direction, which
causes their magnetic fields to add, making the material magnetized.
Describe two methods for creating a magnet. - ANSWER Two methods for creating a
magnet include: (1) stroking a magnetic metal with a magnet; and (2) wrapping wire
around a magnetic metal and passing electric current through the wire.
Explain the law of attraction and repulsion between two magnets. - ANSWER The law
of attraction and repulsion between two magnets states that like magnetic poles repel
each other, while unlike magnetic poles attract each other.
Describe two methods for demagnetizing a magnet. - ANSWER Two methods for
demagnetizing a magnet are vibration and heat.
List the five basic rules that magnetic flux lines follow. - ANSWER The five basic rules
that magnetic flux lines follow are: (1) they have direction or polarity; (2) they always
form complete loops; (3) they cannot cross one another; (4) they tend to form the
smallest possible loops; (5) they can pass through magnetic and nonmagnetic
materials.
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