NCTI Installer Tech Exam Test Questions And
Answers Verified 100% Correct
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.
What is an electromagnet? - 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? - 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.
How do the magnetic fields between two closely spaced parallel wires that are
conducting current interact with each other if the current flow in both wires is in the
same direction? - ANSWER The magnetic fields of two closely spaced parallel wires
that are conducting current in the same direction will add together because the flux
lines will go in the same direction, forming loops around the wires. The flux lines will
attract one another, causing the wires to draw together.
Why is the overall magnetic field created by forming loops of wire stronger than that
created by a straight piece of wire, both having the same current flow? - ANSWER
The overall magnetic field created by forming loops of wire is stronger than that
created by a straight piece of wire because the flux lines in a coil of wire are closer
together, and thus the majority of the flux lines are concentrated in the center or core of
the loops.
Explain how to determine the direction of the magnetic field of an electromagnet. -
ANSWER Use the left-hand rule for electromagnetism in a coil to determine the
location of an electromagnet's north pole, and thus the direction of its magnetic field.
When you wrap the fingers of your left hand around the coil of wire in the direction of
current flow, your thumb will point to the electromagnet's north pole. The direction of
the magnetic field leaves from the electromagnet's north pole and re-enters at its south
pole.
Name three ways to increase the strength of an electromagnetic field. - ANSWER
Three ways to increase the strength of an electromagnetic field are: (1) increasing the
current flow; (2) increasing the number of turns in the coil; and (3) placing an iron core
inside the coil, increasing the flux line density.
What determines the strength of an electromagnetic field and the number of lines of
flux in that field? - ANSWER The magnitude of the magnetomotive force (mmf)
determines the strength of an electromagnetic field and the number of lines of flux in
that field.
What can manufacturers use to actuate (open or close) a reed switch? - ANSWER
Manufacturers can use a permanent magnet or an electromagnet to provide the
magnetic field needed to actuate (open or close) a reed switch.
,The recording head of a tape recorder is actually an ________________ . - ANSWER
The recording head of a tape recorder is actually an electromagnet.
Explain how a basic loudspeaker produces sound. - ANSWER A basic loudspeaker
utilizes both a permanent magnet and an electromagnetic coil to produce sound.
Current produced by a sound wave is made to flow through the voice coil. The
resultant magnetic field of the coil interacts with the magnetic field of the permanent
magnet, which causes the coil to move. The cone to which the coil is attached moves
back and forth in relation to the varying current of the original sound, which causes the
air around the cone to move, thus producing sound.
The amount and direction of rotation of the needle pointer in a D'Arsonval meter
movement are _______________ (proportional/inversely proportional) to the amount
and direction of the applied current. - ANSWER The amount and direction of rotation
of the needle pointer in a D'Arsonval meter movement are proportional to the amount
and direction of the applied current.
To create an electromagnet, - ANSWER Wrap a coil of insulated wire around an iron
bar and pass an electric current through the wire.
Magnetism - ANSWER Was discovered when the Greeks noticed that magnetite
always aligned itself in a north and south direction.
In a magnetic material, - ANSWER Where only some of the magnetic domains are
pointing in the same direction, the magnetic field is weaker.
The strength of an electromagnetic field is - ANSWER Determined by the magnitude of
the magnetomotive force (mmf).
The magnetic field - ANSWER Created by a straight piece of wire is weaker than that
created by forming loops of wire.
Flux lines - ANSWER Always curve around through the body of the magnet to form
complete loops.
Magnetic poles that are ___________ will ____________ each other when those poles
are near each other. - ANSWER Alike, repel
A permanent-magnet loudspeaker - ANSWER Has a cone that moves back and forth in
relation to the varying current of the original sound.
, The left-hand rule for electromagnetism in a wire states that - ANSWER If you wrap
the fingers of your left hand around the wire with your thumb pointing in the direction of
the current flow, your fingers will be wrapped in the direction of the magnetic field.
The recording head of a tape recorder is actually a(an) - ANSWER Electromagnet.
Define an equation. - ANSWER We define an equation as a mathematical statement in
which two quantities are equal.
To what basic principle does each axiom adhere? - ANSWER Each axiom adheres to
the basic principle that whatever is done must be done to both sides of the equation.
Moving a quantity or term from one side of the equal sign to the other side and changing
its sign is called ______________. - ANSWER Moving a quantity or term from one side
of the equal sign to the other side and changing its sign is called transposing.
Which of the following is a true axiom? - ANSWER When A = C and B = C, then A = B
because both are equal to C, which supports the axiom: Quantities equal to the same
quantity are equal to each other.
Simplify and solve the equation: If E = IR then what is the formula for finding I? -
ANSWER E/R.
10 to the power of -3 has a metric prefix of ______. - ANSWER Milli
Name the three basic parts of every electrical circuit. - ANSWER A power source, a
load, and connecting conductors comprise every electrical circuit, when viewed in its
basic form.
Describe the complete path for electrons moving in an electrical circuit. - ANSWER In
an electrical circuit, electrons move from the negative terminal of the power source,
through the load, and back to the positive terminal of the source.
What is the part of the circuit that provides a difference of potential? - ANSWER The
power source, or voltage supply, provides the difference of potential in a circuit.
Give an example of a familiar and commonly used power source. - ANSWER The
battery is a familiar and commonly used power source.
The ____________ is the part of the circuit that uses electrical energy to carry out some
desired function. - ANSWER The load is the device or part of the circuit that uses
electrical energy to carry out some desired function.
Answers Verified 100% Correct
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.
What is an electromagnet? - 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? - 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.
How do the magnetic fields between two closely spaced parallel wires that are
conducting current interact with each other if the current flow in both wires is in the
same direction? - ANSWER The magnetic fields of two closely spaced parallel wires
that are conducting current in the same direction will add together because the flux
lines will go in the same direction, forming loops around the wires. The flux lines will
attract one another, causing the wires to draw together.
Why is the overall magnetic field created by forming loops of wire stronger than that
created by a straight piece of wire, both having the same current flow? - ANSWER
The overall magnetic field created by forming loops of wire is stronger than that
created by a straight piece of wire because the flux lines in a coil of wire are closer
together, and thus the majority of the flux lines are concentrated in the center or core of
the loops.
Explain how to determine the direction of the magnetic field of an electromagnet. -
ANSWER Use the left-hand rule for electromagnetism in a coil to determine the
location of an electromagnet's north pole, and thus the direction of its magnetic field.
When you wrap the fingers of your left hand around the coil of wire in the direction of
current flow, your thumb will point to the electromagnet's north pole. The direction of
the magnetic field leaves from the electromagnet's north pole and re-enters at its south
pole.
Name three ways to increase the strength of an electromagnetic field. - ANSWER
Three ways to increase the strength of an electromagnetic field are: (1) increasing the
current flow; (2) increasing the number of turns in the coil; and (3) placing an iron core
inside the coil, increasing the flux line density.
What determines the strength of an electromagnetic field and the number of lines of
flux in that field? - ANSWER The magnitude of the magnetomotive force (mmf)
determines the strength of an electromagnetic field and the number of lines of flux in
that field.
What can manufacturers use to actuate (open or close) a reed switch? - ANSWER
Manufacturers can use a permanent magnet or an electromagnet to provide the
magnetic field needed to actuate (open or close) a reed switch.
,The recording head of a tape recorder is actually an ________________ . - ANSWER
The recording head of a tape recorder is actually an electromagnet.
Explain how a basic loudspeaker produces sound. - ANSWER A basic loudspeaker
utilizes both a permanent magnet and an electromagnetic coil to produce sound.
Current produced by a sound wave is made to flow through the voice coil. The
resultant magnetic field of the coil interacts with the magnetic field of the permanent
magnet, which causes the coil to move. The cone to which the coil is attached moves
back and forth in relation to the varying current of the original sound, which causes the
air around the cone to move, thus producing sound.
The amount and direction of rotation of the needle pointer in a D'Arsonval meter
movement are _______________ (proportional/inversely proportional) to the amount
and direction of the applied current. - ANSWER The amount and direction of rotation
of the needle pointer in a D'Arsonval meter movement are proportional to the amount
and direction of the applied current.
To create an electromagnet, - ANSWER Wrap a coil of insulated wire around an iron
bar and pass an electric current through the wire.
Magnetism - ANSWER Was discovered when the Greeks noticed that magnetite
always aligned itself in a north and south direction.
In a magnetic material, - ANSWER Where only some of the magnetic domains are
pointing in the same direction, the magnetic field is weaker.
The strength of an electromagnetic field is - ANSWER Determined by the magnitude of
the magnetomotive force (mmf).
The magnetic field - ANSWER Created by a straight piece of wire is weaker than that
created by forming loops of wire.
Flux lines - ANSWER Always curve around through the body of the magnet to form
complete loops.
Magnetic poles that are ___________ will ____________ each other when those poles
are near each other. - ANSWER Alike, repel
A permanent-magnet loudspeaker - ANSWER Has a cone that moves back and forth in
relation to the varying current of the original sound.
, The left-hand rule for electromagnetism in a wire states that - ANSWER If you wrap
the fingers of your left hand around the wire with your thumb pointing in the direction of
the current flow, your fingers will be wrapped in the direction of the magnetic field.
The recording head of a tape recorder is actually a(an) - ANSWER Electromagnet.
Define an equation. - ANSWER We define an equation as a mathematical statement in
which two quantities are equal.
To what basic principle does each axiom adhere? - ANSWER Each axiom adheres to
the basic principle that whatever is done must be done to both sides of the equation.
Moving a quantity or term from one side of the equal sign to the other side and changing
its sign is called ______________. - ANSWER Moving a quantity or term from one side
of the equal sign to the other side and changing its sign is called transposing.
Which of the following is a true axiom? - ANSWER When A = C and B = C, then A = B
because both are equal to C, which supports the axiom: Quantities equal to the same
quantity are equal to each other.
Simplify and solve the equation: If E = IR then what is the formula for finding I? -
ANSWER E/R.
10 to the power of -3 has a metric prefix of ______. - ANSWER Milli
Name the three basic parts of every electrical circuit. - ANSWER A power source, a
load, and connecting conductors comprise every electrical circuit, when viewed in its
basic form.
Describe the complete path for electrons moving in an electrical circuit. - ANSWER In
an electrical circuit, electrons move from the negative terminal of the power source,
through the load, and back to the positive terminal of the source.
What is the part of the circuit that provides a difference of potential? - ANSWER The
power source, or voltage supply, provides the difference of potential in a circuit.
Give an example of a familiar and commonly used power source. - ANSWER The
battery is a familiar and commonly used power source.
The ____________ is the part of the circuit that uses electrical energy to carry out some
desired function. - ANSWER The load is the device or part of the circuit that uses
electrical energy to carry out some desired function.
