Electrical Excellence
What is generally considered to be within the maximum allowable supply voltage variation?
+/- 15%
Which of the following is equal to 100 milliamps? 1.0 amperes, 10 amperes, 0.10 amperes, 0.01 amperes
0.10 amperes
Three 300 ohm 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 Volts
Which of the following is equal to 2.1KW? 21 Watts, 210 Watts, 2100 Watts, 21000 Watts
2100 Watts
How many watts of power are used by a heater operating at 460 volts and drawing 5 amps?
2300 Watts
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
A parallel circuit contains a 18 ohm and a 9 ohm resistor. what is the total resistance?
6 ohms
A transformer has 1000 turns of wire in the primary coil and 500 in the secondary coil. If 120 volts are applied, the output will be:
60 Volts
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 equals 4 amps, what is the source voltage?
60 volts
One horsepower is equal to
746 watts
An ohmmeter should never be connected to:
A live circuit
Which of the following would be considered an inductive load? A resistor. A coil. A motor winding. A live circuit.
A motor winding
A ______ is commonly used on a single phase fractional horse power compressor motor to disconnect the start winding after the motor starts.
Centrifugal switch
A diode is used to:
Control the direction of electron flow
Which of the following statements about current is true? Current flow is the same as voltage Current flow will increase when voltage increases Current flow will increase when resistance increases Current flow will decrease when voltage increases
Current flow will increase when voltage increases
Resistance can be calculated by:
E divided by I
The safety ground conductor is usually what color?
Green
The symbol for current is
I
Voltage can be calculated by:
I times R
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
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
Capacitors are rated in:
Microfarads & Volts
An electron has what kind of charge?
Negative
Which of the following meters must use its internal power to check a load or circuit? Ohmmeter, Voltmeter, Ammeter, Wattmeter
Ohmmeter
Impedance is:
Opposition to alternating current flow
Resistance is:
Opposition to current flow
An electronically commutated motor (ECM) is designed to:
Provide proper air flow under various conditions
Which of the following materials would be best suited for use as a semi-conductor? Copper, Bakelite, Aluminum, Silicon
Silicon
When resistors are wired in parallel:
The current through any one resistor will be the same as the total circuit current
Current flow is:
The flow of electrons in the circuit
A three phase load requires a minimum of:
Three supply lines and a neutral
The electric meter on a house measure the ___ passing through it.
Voltage
Fuses are sized by:
Volts and Amps
Which of the following is the correct formula for determining wattage in an electrical circuit? W = E times I W = E / R W = I / R W = E times R
W = E times I
Which of the following is the symbol for Impedance in an AC circuit? W, X, Y, Z
Z
Any material that will readily release electrons is called:
a conductor
IN a series circuit, the voltage drop across each resistance (load) will:
add up to equal the source voltage
Like charges:
attract
The total resistance of a parallel circuit will be:
less than the smallest resistance
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:
only the 4 watt bulb will light
what is the term used to describe the output side of a transformer?
secondary side
A capacitor analyzer is designed to read:
the capacitance of a capacitor
In electrical wiring, a black colored wire usually indicates:
the hot conductor
