2A Final

Nickel-cadmium (nicad) cells can be charged and discharged about _____ times.

2000

What is the peak voltage of a 277 V RMS AC voltage?

391.68 V

The operating principles of the cathode-ray tube were discovered by _____

J.J Tompson

In a circuit that has both capacitance and resistance, the current will lead the voltage:

by some angle between 0° and 90°

What does the above diagram depict?

exponential curve

An alkaline-manganese C cell size has 4.9 watt-hours per cubic inch.

false

Flux lines pass through a core material with a low permeability better than through a material with a high permeability.

false

The current flowing through a pure capacitive element will lag the voltage by 90 electrical degrees.

false

When resistors of Load 1 are connected in a delta, the line current is the same as the phase current.

false

Using Fleming's left-hand generator rule, which points to the movement of the conductor?

thumb

If Load 3 is pure capacitive, the current and voltage are 90 degrees out of phase with each other and the power factor is zero.

true

When batteries or cells are connected in series, their voltages add, and their current capacities remain the same.

true

Lithium cells can have voltages that range from 1.9 volts to 3.6 volts.

true

The terminals of a motor can be identified using a battery and a(n):

voltmeter

The more discharged a lead-acid battery becomes, the more _________ is formed in the electrolyte and the lower the specific gravity reading becomes.

water

According to NEMA definitions, which of the following is a type of open motor?

weather protected

A wye-connected alternator that has phase voltages of 277 V is feeding two loads. The first load is wye-connected inductors that have 40 Ω of XL. The second load is delta-connected capacitors that have XC of 60 Ω. How much is the alternator phase current?

6.93 A

Which of these formulas is used to calculate capacitive current?

Ic=E/Xc

DC injection braking is used on:

the stationary windings of AC motors

In an inductive AC circuit, when the applied voltage is at its maximum negative value, the current is:

zero

Which of the following is a primary cell?

zinc-air

If the time for one cycle is 0. 1 second, the frequency is:

10 Hz

An RLC parallel circuit has an applied voltage of 240 V. R = 60 Ω, XL = 80 Ω, and XC = 40 Ω. What is the apparent power?

1200 VA

An RLC series circuit has an applied voltage of 240 volts. R = 48 Ω , X L = 100 Ω , X C = 36 Ω , and Z = 80 Ω . What is the total current?

3 A

An RLC parallel circuit has an applied voltage of 240 V. R = 48 Ω, XL = 100 Ω, and XC = 36 Ω. What is angle theta?

40.48°

Reactive power is always

90° out of phase with true power

Which of these formulas is used to calculate inductive VARs?

VARsl=E×Il

When power is applied to a capacitor, it begins to charge to the peak value of the ________.

applied voltage

During ____________, the aluminum ions become aluminum atoms.

electrolysis

Which value is often the simplest measurement to make when using an oscilloscope?

peak to peak

What type of cell cannot be recharged?

primary

When calculating values in an RLC parallel circuit, what does VARSC represent?

reactive power of the capacitor

One of the most common uses for electroplating is the production of pure _____.

metals

When determining bandwidth, what components result in a sharp increase and decrease of current?

High-Q components

The peak-to-peak value of a sine wave is measured from the minimum value in the negative direction to the maximum value in the positive direction.

false

which measures magnitude only?

scalar

Once the sine, cosine, or tangent of the angle has been determined, the angle can be found by using a(n) ______________.

scientific calculator

Capacitors help reduce or eliminate voltage spikes and surges by the current- limiting effect of a capacitor being affected by the frequency.

true

Transformers in which the primary and secondary voltages are 180 degrees out of phase are known as:

unlike-wound transformers

Which of these formulas would be used to determine the resonant value of inductance?

L=1/4pie2Fr2C

One type of non-sinusoidal waveform is the:

square wave

In the above diagram of connected batteries, what is the total voltage?

48V

When current flows through a(n) ___________, a magnetic field is created around it.

conductor

The capacitor-start motor is the single-phase motor type that has the:

highest starting tourqe

What does EP(Load) represent?

phase voltage of the load

Piezoelectricity refers to electricity produced by some materials when they are subjected to _____.

pressure

When using vector addition for inductive reactance and capacitive reactance, the smaller value is eliminated.

true

In a three-phase connection, what is the voltage measured between the lines?

line voltage

_____________ waves are so named because the voltage at any point along the waveform is equal to the maximum, or peak, value multiplied by the sine angle of rotation

sine

In a wye-connected system, the line voltage is higher than the phase voltage by a factor of _____.

square root of three

Another name for the three-phase wye connection is the _______________ connection.

star

To perform a load test on a lead-acid battery, the amount of test current should be _____ times the ampere-hour capacity.

three

Because the current and voltage are both either positive or negative at the same time, watts is always positive.

true

Many AC formulas are based on ____________.

right triangles

In an RC parallel circuit, E T = 120 V, R = 40 Ω , and X C = 30 Ω . What is I T ?

5A

An RLC parallel circuit has an applied voltage of 240 volts. R = 48 Ω, XL = 100 Ω, and XC = 36 Ω. What is the total current?

6.57 A

Which of these formulas would be used to determine the resonant value of capacitance?

C=1/4pie2Fr2L

Which of these formulas is used to calculate circuit power factor?

PF=W/VA

Which of the following motors provides constant speed from no-load conditions to full-load conditions?

syncronous

Which of the following motors is used when the required starting torque is high and speed control is desirable?

compound

A term used to indicate the same value as the RMS value is the _____ value

effective

Because inductive and reactance and capacitive reactance are 180° out of phase with each other in an RLC series circuit, mathematical addition must be used to find their sum.

false

Both AC and DC can be transformed

false

The stationary magnet of a DC motor is represented by the:

field poles

According to the power triangle, the apparent power is:

grater than the true power

At ______ frequencies, the skin effect can have a great effect on the operation of the circuit

high

The advantage of _______________ is that less current is required to produce the same amount of power.

high voltage transmission

What has its primary and secondary winding physically and electrically separated from each other?

isolation transformer

If an RLC parallel circuit contains more capacitive VARs than inductive VARs, the circuit has a _____ power factor

leading

Gas-filled tubes operate with ____________ atmospheric pressure inside the tube.

lower-than-normal

Each of three equal capacitors in series has:

one-third the applied voltage

In a right triangle, the side across from an angle (the side is not one of the two that make the angle) is called the _____.

opposite side

During electrolysis, electrons are removed from what kind of ions and returned to aluminum ions?

oxygen

The impedance of the RLC series circuit is the sum of resistance, inductive reactance, and capacitive reactance.

true

Trigonometry can provide answers to applications such as the necessity to know the height of a tall building.

true

When a voltage is induced in a coil and there is a complete circuit, current flows through the coil.

true

When asking for directions, you are told "Walk three blocks." This is an example of a scalar.

true

A right triangle has two sides that are 9 inches and 12 inches. How long is the hypotenuse?

15 inches

The power factor of an induction motor at no-load conditions can be as low as:

15%

What are typically used to help eliminate voltage spikes and surges?

capacitors

What is the typical capacitance rating of a typical MOV?

1900 pf

A 30-microfarad capacitor is in parallel with a 15-microfarad capacitor. The total capacitance is:

45

Several motors are permitted to be supplied by a single branch circuit as long as each motor is no larger than:

1 hp

The synchronous speed at which a four-pole, 60Hz induction motor operates is:

1,800 rpm

The most common service factor appearing on a motor's nameplate is:

1.15

An RLC series circuit has an applied voltage of 277 volts. The current through the resistor is 3.5 A. What is the apparent power of the circuit?

969.5 VA

Which of these formulas is used to calculate three-phase VARs of a three-phase power circuit?

VARSc=

A delta connected set of windings has a phase voltage of 100 V. What is the line voltage?

100 V

A parallel circuit at resonance has ITANK = 1.00 A, ILINE = 0.05 A, Q = 20, and a voltage across the tank of 500 V. What is the impedance of the tank?

10,000 Ω

What is the true power in a 2A series RL circuit with a 100Ω resistor?

400 W

In an RC parallel circuit, E T = 208 V, R = 68 k Ω , and X C = 56 k Ω . What is the phase angle (angle theta)?

50.53°

In a DC series motor, how much of its full-load torque is developed at starting?

500%

The product of the source voltage and the total current is:

apparent power

If the phase angles of two sine waves are both 0 degrees, then the waves:

are in phase

Using Fleming's left-hand generator rule, which shows the direction of the current induced into the armature?

center finger

An electrolyte may be made from water and an additive such as salt, a(n) _____, or a(n) _____.

acid;alkali

The ___________ can be used to clearly illustrate that if the polarity of the magnetic field is changed or if the direction of armature rotations is changed, the direction of induced current also changes.

Flemings left hang generator rule

In the above image, the magnet is moved toward the coil. What happens to the magnetic field around the coil?

It expands outward of the coil, inducing a voltage in the coil.

In a right triangle, the sum of the squares of two sides is equal to the square of the hypotenuse. This was discovered by a Greek named _____.

Pythagoras

Which of these formulas is used to calculate reactive power?

VARsc=VA2-P2