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NCTI Installer Tech Exam Questions and Answers
NCTI Installer Tech Exam Questions and Answers
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NCTINCTIInstaller Tech ExamExam
Installer Tech/November Questions
and Answers
With 100% Correct Answers 2023
Why do only the outer electrons leave their orbit shells? - Correct 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? - Correct 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. - Correct 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? - Correct 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. - Correct 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? - Correct
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? - Correct
Answer-The number of electrons in the valence shell determines the element category.
How many valence electrons are there in a good conductor? - Correct 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.) - Correct Answer-#1 Silver; #2 Copper; #3 Gold
Why do metals that each have only one valence electron differ in their conductivity? -
Correct 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. - Correct 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? - Correct Answer-A
semiconductor has four valence electrons.
Name the two types of electron current flow. - Correct 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? - Correct 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? - Correct 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? - Correct 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? - Correct
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? - Correct Answer-A coulomb is equal to 6.28
× 1018 electrons.
What is the basic measurement unit of electron current? - Correct Answer-The ampere
is the basic measurement unit for electron current.
Define ampere in terms of coulombs. - Correct 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. - Correct Answer-Potential difference, electromotive force (emf), and
voltageare used interchangeably to refer to the force that causes current flow.
Define electromotive force (emf). - Correct Answer-Emf is the electrical force that
motivates electrons to move in a wire.
What does the term potential difference mean? - Correct 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? - Correct
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? -
Correct 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. - Correct 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? - Correct 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? - Correct Answer-2 MV or 2
million volts.
What are two alternate ways to express 4 kilovolts? - Correct Answer-4 kV or 4,000
volts.
20 milliamperes is the same as ________. (Remember, 1 milliampere = 0.001 ampere.)
- Correct Answer-0.02 amperes
The orbital shell that has a maximum electron capacity of 18 electrons is the
___________ shell. - Correct Answer-Third
A semiconductor material - Correct Answer-Has four valence electrons.
The major factor for determining whether a particular element is a conductor, a
semiconductor, or an insulator is - Correct Answer-The number of electrons in the
valence shell.
Elements that are called conductors - Correct Answer-Have very few valence electrons.
The term voltage normally refers to - Correct Answer-The measurement of the
difference in potential between two charges.
The ampere - Correct Answer-Indicates how many coulombs pass a given point during
1 second.
Electric current is actually produced by - Correct 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? - Correct Answer-The attraction
between the positive nucleus and the negative electron.
5 kilovolts is the same as - Correct Answer-5 kV.
, What would happen if you suspended magnetite by a string and allowed it to swing
freely? - Correct 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? - Correct 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? - Correct 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. - Correct 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. - Correct 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. - Correct 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. - Correct Answer-Two methods for
demagnetizing a magnet are vibration and heat.
List the five basic rules that magnetic flux lines follow. - Correct 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.
What is an electromagnet? - Correct Answer-An electromagnet is a temporary magnet
that is made by applying a potential difference to a wire that is wrapped around a core
of magnetic material.
Does the magnetic field around a wire that is conducting current become stronger or
weaker as the distance from the wire increases? Why? - Correct Answer-The magnetic
field around a current-carrying conductor becomes weaker as the distance from the
conductor increases because the flux lines become farther apart.
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