Electricity
If a step-down transformer has windings with 1000 and 500 turns, what is the induced voltage at the secondary winding if 100 volts is being applied to the primary winding?
50 volts
If three resistances of values 3 Ω, 4 Ω, and 12 Ω are wired in parallel with each other, what is the total resistance of the circuit?
1.5 Ω
The unit of measurement for the charge a capacitor can store is the
microfarad.
If a heated space reaches a maximum temperature of 78°F and a minimum temperature of 71°F, the difference between these two temperatures is referred to as the
temperature swing.
What device is used to produce the control voltage that is used to power the control circuits of a split-type residential central air-conditioning system?
Step-down transformer
A solenoid can be described as
a coil of wire.
If the resistance in a 120-V circuit was 40 Ω, what would the current be in amperes?
3 A
A combination overload device responds to changes in
current and temperature.
What method is most likely to be used to measure the temperature of a liquid contained in an open vessel?
Immersion
A pressure switch that has a cut-in pressure of 30 psig and a differential of 10 psig will operate with
a cut-out pressure of 20 psig.
The opposition to current flow in a circuit is commonly referred to as
resistance.
If there were a current flowing of 5 A in a 120-V circuit, what would the resistance be?
24 Ω
Which of the following is a device consisting of two dissimilar metal wires fastened at one end that, when heated on the fastened end, produces a DC current?
Thermocouple
Consider an R-410A air-conditioning system that is operating with a suction pressure of 118 psig and an oil pump discharge pressure of 185 psig. What is the net oil pressure?
67 psig
The control voltage that is typically used in split-type residential central air-conditioning systems is
24 V.
The nucleus of an atom contains which particles?
Neutrons and protons
The _________ is that part of an atom that moves from one atom to another.
electron
What is the device that consists of two dissimilar metal strips that have different rates of expansion and contraction?
Bimetal
The Bourdon tube reacts to changes in
pressure
What toxic substance can be found in older-generation control devices?
Mercury
Which of the following statements can best be associated with inductance?
A magnetic field is generated when current flows through a conductor.
Undersized wires can cause
voltage drops, tripped circuit breakers, and overheating.
A thermostat is a(n)
automatic control device that responds to changes in temperature.
The thermistor changes its resistance in response to changes in
temperature
The control device that converts a sensed pressure into an electrical signal is the
pressure transducer.