What is the volume of a room that measures 10ft by 20ft with an 8ft ceiling
800
1600
2400
3200
What is the CFM requirement for a 1800 ft2 house with 8 ft ceilings, if five air changes per hour are needed?
400
1200
what is them CFM requirement for an 2400 ft2 house with 8 ft ceilings, if five air changes per hour are needed.
what is the cross sectional area of a 10-in round metal duct
79 in2
200 in2
314 in2
418 in2
how fast does air with a velocity pressure of 0.20in. w.g. move through a round duct
400ft/min
1200ft/min
1600ft/min
1800ft/min
how fast does air with a velocity pressure of 0.20in w.g. move through a square duct?
400 ft/min
1200 ft/min
1600 ft/min
1800 ft/min
What is the advantage of using a tube cutter to cut copper pipe?
it can cut hard or soft copper
it leaves no metal shavings to contaminate the system
it produces a clean, square cut
all of the above
only B & C
spring-type benders may be used on ________?
soft drawn copper
hard copper
all copper pipe
steel pipe
a flaring tool is used to _________.
make a mechanical joint in tubing
measure pipe diameters
remove burrs from piping
separate pipe fittings
a swaging tool is used to _________.
cut copper pipe
solder tubing without the use of couplings
what is one of the advantages of a glass-stem thermometer?
it is very accurate
it is very durable
it comes with a digital readout
none of the above
in discussing human comfort, the temperature most commonly referred to is __________.
dew point
dry-bulb
wet-bulb
fahrenheit
a sling psychrometer uses two glass-stem thermometers. one measures dry-bulb, and the other measures ______.
enthalpy
relative humidity
a standard refrigeration manifold uses what type of element to measure pressure?
bellows
bourdon tube
diaphragm
spring
what is the pressure range of a standard compound gauge on a refrigeration manifold?
0 to 350 psi
0 to 500 psi
30in. Hg to 350 psi
30in. Hg to 500 psi
what is the best tool for removing moisture and noncondensibles from a system before adding refrigerant
manifold gauge
micron analyzer
recovery machine
vacuum pump
a vacuum gauge reads pressure in ______.
inches of mercury
inches of water
microns
psia
psig
which of the following is NOT a method of leak detection?
soap bubbles
electronic
micronic
ultrasonic
to prevent the release of refrigerant into the atmosphere, while removing it from a system what tool is used?
recycling machine
reclaim machine
an anemometer uses a small fan blade to measure ______?
air pressure
air velocity
air volume
static pressure
what is one of the advantages using silver rods for brazing copper?
a lower melting temperature is required
a propane torch is used
no flux is required
no nitrogen purge is needed
what agency regulates cylinders and chemicals transported in a service vehicle?
ASHRAE
DOT
EPA
OSHA
ICE
DMV
LOL
YOLO
What is the maximum safe storage temperature of a refrigerant cylinder filled to 80% capacity by weight?
120 F
125 F
130 F
135 F
which of the following classification of fire extinguishers should be used for an electrical fire?
a
b
c
d
which of the following categories could be considered a hazardous atmosphere in a confined space?
asphyxiation
flammable
toxic
if a ladder is placed against a wall that is 20 ft tall, what is the proper distance away from the wall for the base of the ladder?
3 ft
4 ft
5 ft
6 ft
what is one of the most important safety precautions that you can take when working on electrical equipment
disconnect and lockout power before starting unless testing requires the power to be on
keep one hand in your pocket while working on the power
label all hot wires
wear gloves suitable for high voltages
when does a ground fault circuit interrupter open an electric circuit?
when current travels through a ground path other then the neutral
when the circuit is overloaded
when there is a short circuit
a natural cooling process produced by moisture on the skin changing to low pressure steam is called _______.
conduction
convection
evaporation
radiation
during the heat season, human comfort can be enhanced without changing the temperature of the air by _________.
adding moisture
reducing moisture
increasing air filtration
increasing air speed
during the cooling season, dampers on bypass humidifiers should be ___________.
completely closed
completely open
set to 25% open
set to 50% open
all matter can exist as _________
liquid
gas
solid
stored energy is called ____________ energy
controlled
kinetic
potential
quantum
heat that you can feel and measure directly with a thermometer is called ___________ heat.
absolute
latent
sensible
super
the heat energy change associated with a phase (state) change is called ________.
the amount of heat (BTU) needed to raise the temperature of 1lb of a substance 1 degree is call the ___________ heat of the substance.
specific
the latent heat of infusion is the amount of energy required to change 1 lb of a substance from ________ phase to the ________ phase without changing its temperature.
liquid, vapor
liquid, solid
solid, vapor
vapor, liquid
at 32F, 1lb of ice can changed to 1lb of water by adding _____ BTU.
32
44
144
970
at 212F 1lb of ice can be changed to 1 lb of steam by adding ______ 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 _______.
saturated
stabilized
subcooled
superheated
when a vapor is heated to a temperature higher than its saturation point, both the added heat and the temperature above saturation are called _________.
latent heat
sensible heat
specific heat
super heat
the process of molecules escaping from the surface of a liquid is called ________.
condensation
saturation
subcooling
the process of a solid turning directly into a vapor without going through the liquid state is called _______.
sublimation
superheating
the continuous movement of molecules within a liquid or gas is called ______ energy.
atomic
stored
enthalpy includes both _________ and ________ heat energy.
latent, sensible
latent, specific
sensible, specific
specific, absolute
the measurement of force that gravity exerts is called?
mass
specific matter
volume
weight
the amount of matter in a substance is called
gravity
weight per unit of volume or mass per unit of volume is called?
density
specific gravity
specific mass
specific volume
volume per unit of mass or weight is called?
under standard conditions, air weights approximately _______ lb/ft3
0.055
0.065
0.075
0.085
solve to find the fahrenheit temperature corresponding to 30 celcius .
68
70
86
solve to find the fahrenheit temperature corresponding to 20 celcius
solve to find celsius temperature corresponding to 80 F
-1.1
0
15.6
26.7
solve to find the Celsius temperature corresponding to 60
if the absolute temperature of a gas is doubled, under constant pressure the volume will be _______.
cut in half
doubled
increased by 25%
unchanged
what is the new volume of 1 ft3 of air at 0f when heated to 100f
1
1.2
2
3
if gauge pressure reads 30 psi, what is the corresponding absolute pressure?
15.7
34.7
44.7
60.7
the law that applies to the total pressure exerted by a mixture of gases or vapors is called __________ law.
boyles
charles
daltons
newtons
daves
an ampere is a measurement of what?
electrical charge
electron flow rate
opposition to current
potential energy
voltage is best defined as the ______?
amount of power being used in a circuit
force that moves electrons through a circuit
magnetic field surrounding a conductor
resistance to the flow of electrons
current in a circuit is limited by ______ ?
heat
resistance
temperature
voltage
a substance that permits the free movement of electrons is called a(n) ____________.
conductor
insulator
resistor
semiconductor
which of the following conductors would have the least resistance?
a long, large diameter conductor
a long, small diameter conductor
a short, large diameter conductor
a short, small diameter conductor
if the voltage in a circuit is doubled and the resistance remains the same, the current will _________.
drop to zero
be cut in half
double
stay the same
what is the voltage of a circuit if the resistance is 5 ohms and the current is 5 A?
1 V
2.5 V
10 V
25 V
A circuit has a voltage of 10 V and a current of 5 A. what is the resistances
15
20
50
Ohms sign looks like that, in equations it represented by R for resistance. this not an answer
the total resistance of a series circuit is equal to the _________.
sum of all the resistances in the circuit
first resistance only
last resistance only
average of all the resistances
the total current in a parallel circuit is _______.
measured and divided by the number circuit paths
measured only at the first circuit path
the sum of the currents through the individual paths
the total of the first and the last circuit paths
the rate of doing work is called?
amperage
electricity
power
one kilowatt is equal to?
10 W
100 W
1,000 W
10,000 W
which of the following equations is used to solve for electric power
P = E x I
P = I2 x R
P = E2 / R
All of the above
what is the power in a circuit that has a current of 10 A and a resistance of 10 ohms
1 kW
10 kW
100 kW
not enough information to solve
The voltage induced in each turn of the secondary coil of a transformer is __________?
half the voltage induced per turn of the primary coil
twice the voltage induced per turn of the primary coil
the same as the voltage induced per turn of the primary coil
determined by the ratio of turns in the primary to turns in the secondary
the load rating of a transformer is stated in ________.
amperes
volts
volt-amperes
watts
an ac induction motor consists of a stationary part called the _______ and a rotating part called the ________.
field, armature
primary winding, secondary winding
start winding, run winding
stator, rotor
what is the synchronous speed of a three-phase motor that has six poles and is operated on 60-Hz alternating current?
1200 rpm
3600 rpm
4320 rpm
7200 rpm
how does the power factor of an inductive motor affect efficiency?
the lower the power factor, the less efficient the motor is
the lower the power factor, the more efficient the motor is
the higher the power factor, the less efficient the motor is
the power factor has no effect on efficiency of the motor
which of the following single-phase ac motors does not have a start winding?
capacitor-start, capacitor-run
permanent split-capacitor
shaded-pole
split-phase
a centrifugal switch open the start winding circuit when a capacitor-start motor reaches approximately __________ % of its full speed.
50%
60 - 70 %
75 - 80 %
90 - 100 %
a run capacitor is always connected to the ________ and __________ terminals.
primary, secondary
run , common
start, common
start, run
terminal No.1 on all potential relays is always connected to the __________.
common terminal
run terminal
start capacitor
start terminal
the coil of a voltage relay is between terminal _________ and terminal ________ of the relay
1, 5
1, 2
2, 5
3, 5
what type of ac motor has the highest starting torque and the greatest efficiency?
capacitor-start, capacitor run
three-phase
how many terminals does a dual-voltage three phase motor have?
6
9
12
the primary function of a wiring diagram is to ________.
aid the technician in finding the problem
help the owner repair the problem
provide the location of the components
reduce repair time
how many functions is an individual circuit in a control system designed to control
unlimited
the five basic components common to all schematics are a power supply, a path, a load, a legend, and a ___________?
contactor
relay
switch
thermostat
the intention of the overall schematic is to show how the circuit _________.
components are connected
fails
functions
looks
the type of schematic that provides the most helpful troubleshooting information for the service technician is the __________ diagram.
connection
installation
ladder
pictorial
devices that consume power and convert it to some other form of energy, such as motion or heat are ____________.
contacts
fuses
loads
transformers
the normal dividing line for voltage changes in a schematic is the _________.
fuse
transformer
the part of a schematic that lists and explains the system components is called the _________.
appendex
guide
index
legend
This symbol shown below represents a?
double-pole, double-throw switch
double-pole, single-throw switch
single-pole, double-throw switch
single- pole, single-throw switch
see picture
relays and contactors are ___________ control switches.
electrically operated
manually operated
pressure- activated
temperature- activated
a(n) _________ circuit allows the same current to flow through all of the components.
ac
dc
parallel
series
a(n) _______________ circuit has multiple paths for current flow.
what type of circuits are primarily used in control and safety applications?
continuous
series-parallel
when testing with a voltmeter, you should place the meter __________.
in series with the circuit being tested
in parallel
on the highest possible setting
on the lowest possible setting
what does a resistance reading of 0 ohms indicate.
the circuit is open
the meter needs a new battery
the meter needs to be recalibrated
there is a short circuit
when you use an ohm meter, the circuit being measured must be _________.
energized
in use
isolated from all energy sources
at least 1.5 volts
when you test a switch with an ohm meter, a reading of ________ indicates that the switch is closed
0 ohms
24 V
120 V
infinity
on all meters, digital and analog, the scale used should indicate the measurement ___________
close to the bottom of the range
close to the middle of the range
close to the top of the range
anywhere within the range
when testing across a closed switch in an energized circuit, you should read __________.
infinite resistance
0 V ac
120 V ac
when using a standard clamp-on ammeter, you should ________ before taking a reading.
disconnect all of the wires in the circuit being tested
make sure that the jaws are closed
make sure that the jaws are open
shut down and lockout the equipment being tested
when testing compressor windings, you take the following readings:
C to R: 2 ohms C to S: infinite resistance R to S: infinite resistance whats is the diagnosis?
the compressor is good
the run winding is shorted
the start winding is shorted
the start winding is open
capacitance meters must be used on capacitors _________.
connected in series
connected in parallel
in live circuits
that have been removed from the circuit
when testing a thermostat wire that has been removed from a circuit, you measure 0 ohms between red and white. this indicates that ______________.
the transformer is bad
the wiring is good
there is high resistance in the wire
there is a short
when testing with an ammeter, you should place the meter _____________.
in parallel with the circuit being tested
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