Dc/Ac Final

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

The largest AWG size is which has an area of 211,600 circular mills.

0000

An ohmmeter should always be readjusted to when the scale is changed.

0zero

Rule for base of a ladder

1 foot for every 4 feet

Although inductors have some amount of resistance, inductors that have a Q of or greater are generally considered to be pure inductors.

10

A series circuit contains four resistors and the total resistors have values of 70 ohms, 80 ohms, and The resistance of the circuit is 420 ohms. The value of the fourth resistor is

100 ohms.

A rheostat is a variable resistor with terminals.

2

Article of the National Electrical Code deals with conductors used for general wiring.

210

If four resistors, each with a value of 100 ohms, are connected in parallel, the total resistance of the circuit is

25

Resistors that have a tolerance of plus/minus 20% have color bands.

3

A potentiometer is a variable resistor with terminals.

3.

resistor with bands of yellow, violet, red, and silver would have a value and tolerance of what?

4,700

A series circuit has individual resistance of the circuit is resistor values of 200 ohms. 150 ohms, 50 ohms, and 75 ohms. The total

475 ohms.

The exponential curve describes a rate of certain occurrences and is divided into time constraints.

5

time constants are required to charge or discharge a capacitor.

5

Three resistors, with values of 10 ohms, 20 ohms, and 30 ohms, are connected in parallel and the circuit has a voltage of 120 volts with The total current 20-ohm branch is

6

The most common frequency used in electrical generation in the United States and Canada is hertz,

60

Each time constant of an exponential curve is equal

63.2 Percent

If a parallel circuit has two resistors with values of 10 ohms and 25 ohms, the total resistance of the circuit is ohms.

7.14

A U.S. military study showed that a capacitor operated at one-half its rated voltage will have a life span about times longer than a capacitor operated at its rated voltage.

8

is a line that indicates both magnitude and direction.

A Vector

The total amount of resistance to current flow in a series circuit is equal to the sum of the in that circuit.

A and B

A device that can be used for voltage spike suppression in either AC or DC circuits is the

AMelal oxide varistor.

If more than three conductors are to be used in a raceway, the ampacity of the conductors must be

Adjusted

The temperature of the surrounding air is called the

Amblent air temperature.

angular displacement by which voltage and current are out of phase with each other

Angle theta

What occurs when an intermittent gap between conductors or a conductor and ground permits current to jump between two conductive surfaces.

Arc-Fault

A class _____ fire involves grease, combustible liquids, or gases.

B

A class ____ fire involves energized electrical equipment.

C

are used in industrial applications for power factor correction, as well as in the start windings of many single-phase motors.

Capacitors

Although not considered in the circuit calculations of most circuits, inductance is considered in the circuit calculations of couls that contain motors tranfomers lighting that all contain ____ of wire

Coils

The value of a resistor can often be determined by use of the

Color code

Before current can flow through a circuit, a _____ must exist

Complete path

A ____ is generally made for materials that contain one or two valance electrons

Conductor

A good rule to remember concerning capacitors is that can only flow during time that a capacitor is either charging or discharging.

Current

The advantage of high-voltage transmission is that lessCurrent is required to produce the same amount of power.

Current

In parallel circuits, when all resistors are of equal value the total resistance is equal to the value of one individual resistor

Divided by the number Of resistors

a(n) The ground point that is made by physically driving an object, such as a ground rod, into the ground is called

Earth ground.

When determining the conductor size for a particular application, you are determining the maximum current a conductor can carry.

False

A capacitor has capacitance of one when a change of one volt across its plates results in a movement of one coulomb.

Faret

resistors have only one ohmic value, which cannot be changed or altered.

Fixed

When using the color code to determine the value of a resistor, the band is the tolerance band, when the tolerance of the resistor is 5% or 10%.

Fourth

A -wave rectifier is one that changes both positive half and the negative half of the AC wave form into DC.

Full

A conductor connected to the case of an appliance to provide a low-resistance path to ground is called a _____ conductor

Grounding

Electrical current will flow through the ______ conductor only when a circuit fault develops

Grounding

The polarity of the voltage is determined by the polarity of the magnetic field in relation to the direc of movement.

Induced

When reading an ohmmeter scale, the value of resistance shown at the far left end of the scale is

Infinty 8

Never work on an energized circuit unless

It is not possible to disconnect the power

Reactance is symbolized by the letter

L

In a pure capacitive circuit, the current

Leads the applied volatge by 90 degrees

The most common way for producing electricity is

Magnetism

When using the color code to determine resistor values, the third band is called the band.

Multiplier

The amount of current leaving the source

Must equal the current returning to the source

A _____ charge formed by an excess of electrons

Negative

The mission of the ____ is to ensure safe and healthful workplaces in the United States.

None

capacitors are not sensitive to polarity connection.

Nonpolarized

A ______ is the amount of resistance that allows one ampere of current to flow when the applied voltage is one volt

Ohm

I'm it's simplest form, ____ states that it takes one volt to push one amp through one ohm

Ohms law

Polarized capacitors can be in

Only DC

is the ratio of true power to apparent power.

Power Factor

The Q

Quality.

When a capacitor is connected in a circuit with a resistor, the amount of time needed to charge the capacitor time constant.

RC

The AC voltage that will produce the same amount of power as a like value of DC voltage is called the value,

RMS

A is used to change alternating current into direct current.

Rectifier

In a parallel circuit,the amount of current flowing through each resistor is inversely proportional to its

Resistance

RMS stands

Root mean square

21. A circuit is a circuit that has only one path for the current to flow.

Series

The most common of all AC waves is the

Sine wave.

A large amount of voltage that exists for a very short period of time is called a voltage

Spike

Alternating current can be for the purpose of transmission and then when it is 'to be used by a device.

Steped up/Down

The stretching of the atoms of the dielectric is called dielectric

Stress

NEC® 110.14(C) states that the temperature rating of a conductor must be selected so as not to exceed lowest temperature rating of any connected conductor, termination or device.

True

When determining conductor size for an area where ambient temperature is a concern, you must divide the needed current by the correction factor.

True

Reactive power is measured in

VARS

Any electron located in the outer shell of an atom are known as _____ electrons

Valence

capacitors generally contain a set of moveable plates that allow capacitance to be changed.

Variable Capacitors

______ is defined as electromotive force

Volt

is the force that pushes the electrons through a resistance.

Voltage

are the number of turns of wire, the strength of the magnetic field, the speed of the cutting action.

Voltage Induced

are used to provide different voltages between certain points of a circuit.

Voltage dividers

indicates the amount of voltage necessary to push the current through the limiting element.

Voltage drop

The test instrument used to measure voltage in a circuit is called

Voltmeter

Electrical energy must be changed or converted into some other form of energy before there can be

Watts

all the parts of the circuit,

Watts

resistors can operate at higher temperatures than any other type of resistor.

Wire wound

Impedance is symbolized by the letter

Z

The amount of voltage required to push the electrons through the circuit is determined by the amount of

a and b

Which of the following conditions must be met before conductors are permitted the NEC to be run in parallel?

a and c only

A circuit with little or no resistance in it is called

a short circuit

If a clamp-on ammeter is clamped around more than one power line of a 240 V circuit, the meter will read volts.

a.

resistors are fixed resistors that are made by winding a piece of resistive wire around a ceramic core.

a.None of the above

Carbon resistors will change their value because of

age overheating either a or c

In a parallel circuit, the total resistance is equal to the

all of the above only

The unlike the voltmeter, is a very low-impedance device.

ammeter

In a series circuit, the is the same at any point in the circuit.

amperage

If a series circuit has three resistors and two amps flow through each resistor, the total amperage for the circuit is

amps. 2

A wire's ability to carry current is known as its

anmpacity.

The total amount of power in a circuit is equal to the sum of the power used by all the parts.

any of the above

The power of a resistive-inductive series circuit can be found when a voltmeter and ammeter are used to measure the circuit voltage and current and then these measured values are multiplied together.

apparent

Digital meters that do not contain a range setting control are known as meters.

autoranging

The value must be found when a sine wave AC voltage is changed into direct

average

Probably the greatest single advantage of alternating current is that it can

be trans formed.

When the voltage to the capacitor becomes too great, the dielectric breaks down and allows current to flow between the plates, resulting in the capacitor

becoming shorted

Nonpolarized capacitors can be used in

both AC and DC

When a capacitor is connected to a DC circuit and the voltages across both plates are equal, the flow electrons stops and the capacitor is

charged

According to Ohm's law, an increase of resistance must cause a proportional decrease of

current

Each completed wave form of a sine wave is called a(n)

cycle cycle

A location that is covered and not likely to be saturated by water is a

damp

A circular mil is the of the wire in mils squared.

diameter

The insulating material used in capacitors is called the

dielectic

The voltage rating of a capacitor is actually the voltage rating of the

dielertric

A location that snot normally subject to dampness or wetness is called a location.

dry

Reversing the polarity of a -type electrolytic capacitor will permanently damage the capacitor.

dry

Polarized capacitors are generally referred to as

electoylitic capacitors.

The advantage of is that they can have very high capacitance in a small case.

electrolytic

A capacitor stores energy in a(n) field.

electrostatic

The basic unit of capacitance is the

farad

An inductor stores energy in a(n)

field. electromagnetic

VARS is an abbreviation

forVots Arnos Reactance

In a sine wave, the number of complete cycles that occur in one second is called a

frequency

The higher the the faster a capacitor will charge and discharge.

frequency

The standard measure of inductance is the

henry

Connecting capacitors in parallel has the effect of the plate area of one capacitor.

increasing

When reading a digital meter, the symbol "mV"

indicates_mili volts

A coil wound on a nonmagnetic core material such as wood or plastic is referred to as

inductor. air core

The reciprocal of any number is that number divided

into 1

A coil wound on a core made of magnetic material such as silicon steel or soft iron is referred to as a(n)

iron core

The current in a pure resistive circuit

is in phase with the applied voltage

The disadvantage of the metal film resistor is that

it costs more than carbon resistors

The current in a pure inductive circuit

lags the applied voltage by 90 degrees

In the early days of electric power generation, Thomas Edison proposed powering the country with

low-voltage direct current

The principle of states that whenever a conductor cuts through magnetic lines of flux, a voltage is induced into the conductor.

magnetic induction

A device that measures insulation resistance in millions of ohms is called a(n)

megger

A is a piece of wire one foot long and one mil in diameter.

mil-foot

When working with electrical equipment that requires sensitive adjustments, resistors are usually used.

multiturn variable

A point when current reaches a junction point

node

A circuit contains elements of both series and parallel circuits.

none of the above

The is used measure resistance.

ohmmeter

The must provide its own source of power.

ohmmeter

Capacitive reactance is measured in

ohms

Impedance is measured

ohms

Inductive reactance can be computed when the values of inductance and frequency are known and is

ohms

Given the voltage and the resistance, the amount of current flow in a circuit can be determined by using

ohms law

A diode permits current to flow in

one direction(s).

Square waves are generally produced by electronic devices called

oscillators

Avoltmeter is designed to be connected in with the circuit to be measured.

parallel

In a circuit, the voltage across any circuit branch is the same as the total voltage.

parallel

The total resistance of a circuit is always less than the resistance of the lowest value resistor in the circuit.

parallel

circuit has more than one path for current flow.

parallel

are circuits that have more than one path for current flow.

parallel circuits

The is measured from zero to the highest value obtained in either the positive or negative direction.

peak

d. The value is measured from the maximum value in the positive direction to the maximum value in the negative direction.

peak-to-peak

When a capacitor becomes charged, the plate with the lack of electrons has

positive.

Capacitors charge and discharge at a(n)

rate. exponential

VARS is the amount of power in a resistive-inductive circuit.

reactive

Connecting capacitors in series has the effect of increasing the distance between the plates, which capacitance of the circuit.

reduces

The pulses of pulsating direct current are often referred to as

ripple

An ammeter is used to measure current and must be connected in with the load.

series

In a circuit, the sum of the voltage drops of the individual resistors must equal the applied voltage.

series

circuit has only one path for current flow.

series

d. In a circuit, the current is the same at any point in the circuit.

series

The wave is produced by all rotating machines.

sine

When using a megger to test a circuit for grounds or shorts, the meter should be set

slightly higher than the circuit voltage

In a series circuit, the sum of the voltage drops equals

the applied voltage

indicates the plus and minus limits of a resistor's ohmic value.

tolevance Band

The across any branch of a parallel circuit is the same as the applied voltage.

voltage drop

In magnetic measurement, 100,000,000 lines of magnetic flux are equal to one

weber

The two types of electrolytic capacitors are the

wet and dry


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