NATE CORE EXAM QUESTIONS WITH
CORRECT DETAILED ANSWES
GRADED A+
What is thermal expansion? - Answer-it is when solids and liquids expand with increase
in temperature.
What is diffusion? - Answer-It is the continuous motion of the molecules in a liquid or
gas.
What is enthalpy? - Answer-It is the total heat energy contained in a substance, which
includes both sensible heat and latent heat.
What is mass? - Answer-It is the amount of matter in something.
What is weight? - Answer-It is a measure of the force that gravity exerts on something.
Which density does the HVACr industry use? - Answer-Weight density.
What is weight density stated as? - Answer-Ib/Ft^3
Temperature can affect what property of matter? - Answer-Density.
What is the inverse if density called? - Answer-Specific volume.
Specific volume is stated as what? - Answer-Ft^3/lb
Most of the world uses what system of measurement? - Answer-Metric system. (SI)
What temperature does water freeze at? - Answer-32 degrees Fahrenheit or 0 degrees
Celsius.
What is the conversion equation from Celsius to Fahrenheit? - Answer-1.8 x Degrees
Celsius + 32
How do you convert Fahrenheit to Celsius? - Answer-Degress Fahrenheit - .8
What is the point at which heat no longer exists at? - Answer-Absolute zero.
What does Fahrenheit have to be converted to in order to get absolute temperature? -
Answer-Rankine (R).
,What does Celsius have to be converted to in order to get absolute temperature? -
Answer-Kelvin (K).
What is Charles law? - Answer-At constant pressure, the volume of a gas is directly
proportional to its absolute temperature.
What is Boyle's Law? - Answer-The volume of a gas decreases when the pressure is
increased.
What is Dalton's Law? - Answer-The total pressure of a gas mixture is equal to the sum
of the pressure that each gas would exert independently.
At 212 Degrees F, 1 pound of water can be changed to 1 pound of steam by adding
how much Btu? - Answer-970 Btu.
When liquid and vapor phases of a substance exist together, and no more liquid can
vaporize without more energy being added the vapor is said to be what? - Answer-
Saturated.
When a vapor is heated to a temperature higher than its saturation point, both the
added heat and the temperature above saturation is called what? - Answer-Superheat.
The process of molecules escaping from the surface of a liquid is called what? -
Answer-Evaporation.
Weight per unit of volume or mass per unit of volume is called? - Answer-Density.
Volume per unit of mass or weight is called? - Answer-Specific volume.
Under standard conditions air weighs approximately what? - Answer-0.075 ln/Ft^3
How to do you convert gauge pressure to absolute pressure? - Answer-Add 14.7 PSI
What is a coulomb? - Answer-it is as measurement of the quantity of electrical charge
what is an ampere? - Answer-It is the rate of flow of electrical charge through a circuit
What is a volt? - Answer-it is a measure of potential energy. It is the force or pressure
that pushes electrons through an electric circuit
What is voltage also known as? - Answer-electromotive force (EMF) or potential
difference
What is an Ohm? - Answer-the ohm is a measure of the resistance, or opposition, to the
flow of current in a circuit
, What is a conductor? - Answer-it is a substance that permits the free motion of a large
number of electrons with a low resistance
What is the most commonly used conductor because of its low resistance and cost? -
Answer-copper wire
How does size affect resistance? - Answer-The larger the diameter the easier it is for
electrons to move. The shorter the distance the lower the resistance
how does temperature affect resistance? - Answer-increase temperature increases
resistance
What are some examples of good conductors? - Answer-Copper. / Silver. / Gold. /
Aluminum.
What are some examples of insulators? - Answer-Plastic. / Air. / Glass. / Rubber. /
Ceramics.
What does it mean when the current is directly proportional to the applied voltage? -
Answer-it means if the voltage increases the current will also increase.
What is direct current? - Answer-Current that flows in only one direction
What can direct current be produced by? - Answer-Chemical action. (Batteries) and DC
generators.
Diodes or rectifiers that conduct electricity in one direction frequently do what? -
Answer-They convert AC to DC.
A current that alternates is called what? - Answer-Alternating current.
What is Ohm's Law? - Answer-V or E = IxR (V and E both refer to voltage)
What is a series circuit? - Answer-A circuit that has only one path for the elecric current
to flow.
What are the three rules for a series circuit? - Answer-1. I1=I2=I3= I Circuit / 2.
E1+E2+E3= Circuit / 3. R1+R2+R3= R Total
What is a parallel circuit? - Answer-A circuit that has more than one path for electric
current to flow.
What are the three rules for a parallel circuit? - Answer-1. I1+I2+I= I Circuit / 2.
E1=E2=E3= E Circuit / 3. 1/R1+1/R2+1/R3=1/R Total
CORRECT DETAILED ANSWES
GRADED A+
What is thermal expansion? - Answer-it is when solids and liquids expand with increase
in temperature.
What is diffusion? - Answer-It is the continuous motion of the molecules in a liquid or
gas.
What is enthalpy? - Answer-It is the total heat energy contained in a substance, which
includes both sensible heat and latent heat.
What is mass? - Answer-It is the amount of matter in something.
What is weight? - Answer-It is a measure of the force that gravity exerts on something.
Which density does the HVACr industry use? - Answer-Weight density.
What is weight density stated as? - Answer-Ib/Ft^3
Temperature can affect what property of matter? - Answer-Density.
What is the inverse if density called? - Answer-Specific volume.
Specific volume is stated as what? - Answer-Ft^3/lb
Most of the world uses what system of measurement? - Answer-Metric system. (SI)
What temperature does water freeze at? - Answer-32 degrees Fahrenheit or 0 degrees
Celsius.
What is the conversion equation from Celsius to Fahrenheit? - Answer-1.8 x Degrees
Celsius + 32
How do you convert Fahrenheit to Celsius? - Answer-Degress Fahrenheit - .8
What is the point at which heat no longer exists at? - Answer-Absolute zero.
What does Fahrenheit have to be converted to in order to get absolute temperature? -
Answer-Rankine (R).
,What does Celsius have to be converted to in order to get absolute temperature? -
Answer-Kelvin (K).
What is Charles law? - Answer-At constant pressure, the volume of a gas is directly
proportional to its absolute temperature.
What is Boyle's Law? - Answer-The volume of a gas decreases when the pressure is
increased.
What is Dalton's Law? - Answer-The total pressure of a gas mixture is equal to the sum
of the pressure that each gas would exert independently.
At 212 Degrees F, 1 pound of water can be changed to 1 pound of steam by adding
how much Btu? - Answer-970 Btu.
When liquid and vapor phases of a substance exist together, and no more liquid can
vaporize without more energy being added the vapor is said to be what? - Answer-
Saturated.
When a vapor is heated to a temperature higher than its saturation point, both the
added heat and the temperature above saturation is called what? - Answer-Superheat.
The process of molecules escaping from the surface of a liquid is called what? -
Answer-Evaporation.
Weight per unit of volume or mass per unit of volume is called? - Answer-Density.
Volume per unit of mass or weight is called? - Answer-Specific volume.
Under standard conditions air weighs approximately what? - Answer-0.075 ln/Ft^3
How to do you convert gauge pressure to absolute pressure? - Answer-Add 14.7 PSI
What is a coulomb? - Answer-it is as measurement of the quantity of electrical charge
what is an ampere? - Answer-It is the rate of flow of electrical charge through a circuit
What is a volt? - Answer-it is a measure of potential energy. It is the force or pressure
that pushes electrons through an electric circuit
What is voltage also known as? - Answer-electromotive force (EMF) or potential
difference
What is an Ohm? - Answer-the ohm is a measure of the resistance, or opposition, to the
flow of current in a circuit
, What is a conductor? - Answer-it is a substance that permits the free motion of a large
number of electrons with a low resistance
What is the most commonly used conductor because of its low resistance and cost? -
Answer-copper wire
How does size affect resistance? - Answer-The larger the diameter the easier it is for
electrons to move. The shorter the distance the lower the resistance
how does temperature affect resistance? - Answer-increase temperature increases
resistance
What are some examples of good conductors? - Answer-Copper. / Silver. / Gold. /
Aluminum.
What are some examples of insulators? - Answer-Plastic. / Air. / Glass. / Rubber. /
Ceramics.
What does it mean when the current is directly proportional to the applied voltage? -
Answer-it means if the voltage increases the current will also increase.
What is direct current? - Answer-Current that flows in only one direction
What can direct current be produced by? - Answer-Chemical action. (Batteries) and DC
generators.
Diodes or rectifiers that conduct electricity in one direction frequently do what? -
Answer-They convert AC to DC.
A current that alternates is called what? - Answer-Alternating current.
What is Ohm's Law? - Answer-V or E = IxR (V and E both refer to voltage)
What is a series circuit? - Answer-A circuit that has only one path for the elecric current
to flow.
What are the three rules for a series circuit? - Answer-1. I1=I2=I3= I Circuit / 2.
E1+E2+E3= Circuit / 3. R1+R2+R3= R Total
What is a parallel circuit? - Answer-A circuit that has more than one path for electric
current to flow.
What are the three rules for a parallel circuit? - Answer-1. I1+I2+I= I Circuit / 2.
E1=E2=E3= E Circuit / 3. 1/R1+1/R2+1/R3=1/R Total
