HVAC 202 Final Exam Study Guide Part 1

100 milliamps=

0.10 amps

Three 300 ohms resistors are wired in parallel. The total resistance equals ?

100 ohms

The voltage to ground of a "high Leg" or Stinger Leg" on a three phase open Delta System will be approximately

208

Which of the following is equal to 2.1KW?

2100 watts

How many watts of power are used by a heater operating at 460 volts and drawing 5 amps?

2300

A transformer has 1000 turns of wire in the primary coil and 2000 turns in the secondary coil. If 120 volts are applied, the output voltage will be;

240 volts

Three defrost heaters, each 15 ohms are wired in parallel to a 120 volt power supply. How many watts of power will be used?

2880 Watts

Which of the following is generally considered to be within the maximum allowable (plus or minus) supply voltage variation?

5%

A parallel circuit contains a 18 ohm and a 9 ohm resistor. The total resistance equals?

6 ohms

How much resistance must be placed in a 120 volt circuit in order to limit the current to 2 amps?

60 ohms

A parallel circuit consists of three resistors. R1= 30 ohms R2 = 15 ohms R3 = 10 ohms If the current through R2 = 4 amperes, what is the source voltage?

60 volts

1 horsepower =

746 watts

Any material that will readily release electrons is called

Conductor

The flow of electrons in the circuit

Current flow

Resistance can be calculated by

E/I

The safety ground conductor is usually colored coded

Green

The symbol for current is

I

Voltage can be calculated by

I x R

Opposition to alternating current flow

Impedance

Repel one another.

Like charges

Capacitors are rated in:

Microfarads and Volts

Which of the following meters must use its internal power to check a load or circuit?

Ohmmeter

Resistance is

Opposition to current flow

What is the term used to describe the output side of a transformer?

Secondary side

Which of the following materials would be best suited for use as a semi-conductor?

Silicon

Fuses are sized by

Volts and amps

What is the correct formula for wattage in an electrical circuit?

W= E times I

Which of the following is the symbol for Impedance in an AC circuit ?

Z

An ohmmeter should never be connected to

a live circuit

An electron has

a negative charge

In a series circuit , the voltage drop across each resistance (load) will;

add up to equal the source voltage

Two 120 volt incandescent light bulbs are wired in series, one is a 60 watt bulb, the other is a 4 watt bulb. The result would be:

both bulbs light

A diode is used to?

control the direction of electron flow

Which of the following statements about current is true?

current flow will increase when voltage increases

A _______is commonly used on a single phase fractional horse power compressor motor to disconnect the start winding after the motor starts.

current relay

Which of the following would be considered an inductive load?

electric motor

The capacitor start-capacitor run (CSCR) motor provides;

high starting torque and running torque

If the conductor in an AC circuit is wound into a coil, the resulting EMF opposes the supply voltage. This opposition is called?

inductive reactance

The total resistance of a parallel circuit will be

less than the smallest resistance

When current flows, a ____________ is produced around the conductor.

magnetic field

When testing a capacitor with an analog or digital ohmmeter, the meter should:

measure low resistance then return to high reading

Single phase motor speed is determined by the

number of stator poles

An electronically commutated motor (ECM) is designed to

provides proper air flow under various conditions

A capacitor analyzer is designed to read

the capacitance of a capacitor

Direction of rotation of a single phase induction motor is determined by;

the direction of current flow through the start winding

In electrical wiring a black colored wire usually indicates

the hot conductor

When resistors are wired in parallel

the voltage drop across each resistor will be the same as the applied source voltage

A three phase load requires a minimum of

three supply lines

A 240 volt, 4 wire circuit can be split into two; 120 circuits.

two 120 volts circuits between the hot legs and neutral

The electric meter on a house measures the ______ passing through it.

wattage