Fundamentals of Electricity - FINAL EXAM Study Guide
DC
The d'Arsonval meter movement is operated by applying ____ current to the coil.
Fleming
The direction of induced current can be determined by used ____'s left hand generator rule.
domains
The regions formed in the molecular structure of magnetic metals are sometimes called magnetic ____.
saturation
When magnetic material's molecules are all lined up, and increases in current flow no longer cause increases in magnetic field strength, the material has reached ____.
current
When using the left hand generator rule, the center finger points to the direction of ____.
closed
A complete circuit is often referred to as a(n) ______ circuit.
False
T or F: Matter can exist in only two states: solid or liquid.
False
T or F: Most lightning discharges associated with a cloud occur between the cloud and the ground.
short
There is very little resistance and a large amount of current flows in a(n) ______ circuit.
wire-wound
What type of fixed resistor is made by winding a piece of resistive wire around a ceramic core? What type of resistors are generally used when a high power rating is needed?
electromagnet
What type of magnet depends on flowing current to produce a magnetic field?
permanent magnets
What type of magnets do not require any power or force to maintain their field?
multiturn variable
What type of resistor operates by moving the wiper arm with a screw of some number of turns?
fixed
What type of resistors can only have one ohmic value?
Lenz's Law
When a closed loop of wire cuts through magnetic flux lines, a current is induced into the loop. The current in the loop sets up a magnetic field that is in opposition to the original magnetic flux. This is _______. An induced voltage opposes the motion that causes it according to ______.
declination
The angular difference between true north and magnetic north is known as the angle of ___.
Direct
What type of current flows in only one direction?
metal glaze
What type of fixed resistor is made by combing metal with glass and then applying it to a ceramic base as a thick film?
variable
A resistor whose values can be varied over a range of values is called a ________ resistor.
potentiometer
A variable resistor with three terminals is called a _____.
high
A voltmeter has very ____ resistance connected in series with the meter movement.
multirange
A(n) _____ ammeter operates on more than one range by connecting the meter movement to different shunts.
insulators
Electrostatic charges occur on ________.
will not
If a circuit is open, current _____________ flow.
man-made
In a clothes dryer, the greatest static charge generally are built up on _______ fabrics.
electron
Magnetism can be explained in terms of ___ spin patterns.
longer
Manmade permanent magnets retain their magnetism ___ than natural magnets.
dry
Nuisance static charges are more likely to occur when the air is _____.
semiconductor
Selenium is a(n) _________.
true
T of F: Earth contains magnetic poles.
1,000
The Greeks were the first to discover electricity about ______ years ago.
an ohmmeter
What meter measures resistance? What meter must NEVER be connected to a circuit when the circuit power is turned on?
wattmeter
What meter measures true power in a circuit?
Electron
What part of an atom has a negative charge?
resistive
What type of load contains pure resistance?
high
The series ohmmeter is used to measure ____ values of resistance.
left
To locate the pole of an electromagnet, use the ___ hand rule.
Tera
What standard prefix in engineering notation indicates multiplication by 1,000,000,000,000?
Giga
What standard prefix in engineering notation indicates multiplication by 1,000,000,000?
air filter
A precipitator is a type of __________.
arrestor
A lightning protection device that is grounded at one end, with the other end close to but not touching the object to be protected, is called the lightning ________.
shunt
A low resistance device used to conduct most circuit current away from the meter movement is an ammeter _____.
grounded
A neutral conductor is also referred to as the _________ conductor.
oppose
Inductors always ___ a change of current.
opposite
Bringing a charged test object near the ball of a charged electroscope causes the leaves to move closer together. This indicates that the test object charge is the _____ polarity as the electroscope charge.
hertz
Frequency is measured in ____.
eddy current and hysteresis
Losses in the core of iron core inductors include ____ and ____.
opposite
If a conductor is moved upward, the polarity of induced voltage is reversed and the current flows in the ____ direction.
is
If a permanent magnet is cut into pieces, each piece ___ a separate magnet.
ground to the cloud
If a thundercloud has a positive charge, the current in the lightning bolt will flow from the _______.
False
In electrical schematics, the symbol used to represent a resistor is standard.
True
T or F: Matter has mass and occupies space.
flux
Magnetic lines of force are referred to as ___.
bump
The theory stating that current flow is produced when an electron from one atom knocks electrons of another atom out of orbit is generally called the _______________ theory.
iron nickel cobalt
The three substances that form natural magnets are ____.
ohm
The unit of resistance to current flow is the ____________.
outer
The valence shell of an atom is the _________ shell.
less than
The velocity of AC through a conductor is ________ the speed of light.
True
T or F: The value of a resistor can often be determined by the "color code."
flux density
In the English system of measure, magnetic strength is measured in terms of ____.
magnetomotive force
In the English system, the total force producing a magnetic field is the _____.
electrons
Insulators are the only materials that can hold ________ stationary.
True
Lightning rods provide an easy path to ground for current.
electromagnetic induction
When a conductor cuts magnetic lines of force, a voltage i inducted into the conductor. This principle is called ___.
rod
When an object protected by a lightning ____ is struck by a lightning bolt, it will bleed the lightning discharge to ground before the protected object can be harmed.
loading
When the connection of a meter to the circuit changes the entire circuit operation, this is known as the ___ effect.
four
A semiconductor contains _______ valence electrons.
series
An ammeter is connected in ____ with the load to permit the load to limit current flow.
seven or eight
An insulator is a material containing _________ valence electrons.
repel attract
A basic law of physics states that like charges ________ and opposite charges ___________.
120 V
An electric circuit has a resistance of 10 ohms. the current is measured to be 12 A. How many volts are applied to the circuit?
10 A
An electrical circuit has a voltage of 50 V and a resistance of 5 ohms. What is the current? Use E=IR and work it out...
40 ohms
An electrical motor is running on 120 V. The current is measured to be 3 A. How many ohms of resistance is the motor? Use E=IR and work it out...
electrons
Electrical current is the flow of ________________.
5
Exponential curves are always divided into ___ time constants.
three
How many color bands are used on resistors that have a tolerance of +/-20 percent?
average
If an AC waveform is rectified and converted into DC, the voltage value that results is the ___ value.
demagnetized
If an object is placed in the field of a strong electromegnet connected to an AC line, the object will be ___.
reverses the polarity of the induced voltage
If voltage is being induced into a conductor by electromagnetic induction, reversing the direction of motion of the conductor will ____.
true
In a DC circuit, the product of volts times the amperes is called the ____ power.
oscillators
Square waves are generally produced by electronic devices called ____.
are not
Static electricity refers to electrons that ______ moving.
False
T or F: A thundercloud contains only positive electric charges.
True
T or F: An electroscope can be used to determine the polarity of an electrostatic charge.
False
T or F: Both AC and DC can be transformed.
True
T or F: Copy machines operate on the principle of static electricity.
False
T or F: Current always flows from positive to negative.
False
T or F: During normal operation a typical 120 V appliance circuit, current flows through the hot, grounding, and neutral conductors.
true
T or F: If current is flowing in a circuit containing an inductor and the power switch is opened, the magnetic field surrounding the inductor collapses and induces voltage into the inductor, resulting in a voltage spike.
skin
The ___ effect occurs when AC induces eddy currents into the conductor, which cause the electrons to be repelled toward the outer surface of the conductor.
tolerance
The _____ of a resistor indicates the plus and minus limits of a resistor's ohmic value.
watts
The amount of electrical power being used in a circuit is measured in ____________.
residual magnetism
The amount of magnetism left in a material after the magnetizing force has stopped is called ___.
nuisance
The shock that results from walking across a carpet and touching a doorknob is an example of a(n) ______ static charge.
molecule
The smallest part of a compound that still remains the properties of that compound is a(n) __________.
RMS
The square root of the mean of the square of the instantaneous currents is known as ____.
Ohm's
The statement, "In a DC circuit, the current is directly proportional to voltage and inversely proportional to resistance," is known as _____________ law.
composition carbon
What type of fixed resistor is made from a compound of carbon graphite and resin bonding material?
from negative to positive
Within a lightning bolt, current flows ______.
gold
What color used as the multiplier band means to divide the combined first two numbers by 10?
Attraction
What for is demonstrated in objects with unlike charges?
Repulsion
What force is demonstrated in objects with like charges?
negative
Conventional current flow theory states that current flows from the most positive point to the most ______________ point.
unidirectional
Direct current is described as _______________.
cycle
Each complete waveform of 360 degrees is called a _____.
magnetite
Lodestone is a name for a naturally occurring magnetic material is also called ____.
multirange
Most voltmeters are _____ voltmeters, meaning they are designed to use one meter movement to measure several ranges.
ampere
One coulomb per second is equal to one _________.
arrestors
Power lines are often protected by lightning ______ that exhibit a very high resistance at the normal voltage of the line.
photons
Producing electricity from light involves the use of particles called ____________.
voltage dividers
Resistors functioning as ____ are used in applications involving field effect transistors (FETs) and multi-range voltmeter circuits.
high power circuits
The low impedance voltage tester is most suitable for use in ___.
one
The magnetic quantity Weber (Wb) is equal to 100,000,000 lines of flux. If a conductor cuts through one Weber per second, then a voltage of ___ volt is induced into the conductor.
peak
The maximum point of a waveform is called the ____.
permeability
The measure of a material's ability to be magnetized is called ___.
reluctance
The measure of a materials's resistance to magnetism is known as ___.
south
The north magnetic pole of a compass needle is attracted to the ___ magnetic pole of the earth.
neutrons and protons
The nucleus of an atom contains _________.
frequency
The number of cycles completed in one second is called a ____.
negative
The precipitator uses high voltage DC power supply to provide a set of wires with a positive charge and a set of plates with a ______ charge.
a galvanometer
What meter features a wire coil suspended between permanent magnet poles and operates on very tiny amounts of current?
voltmeter
What meter is designed to be connected directly across the power source?
Proton
What part of an atom has a positive charge?
Neutron
What part of an atom has no charge?
Mega
What standard prefix in engineering notation indicates multiplication by 1,000,000?
kilo
What standard prefix in engineering notation indicates multiplication by 1,000?
linear
What type of AC waveform features voltage rising at a constant rate with respect to time?
carbon film
What type of a fixed resistor is made by applying a film of carbon to a ceramic rod?
short
What type of circuit generally occurs when the conductors leading from and back to the power source become connected?
Alternate
What type of current reverses its direction of flow at regular intervals?
metal film
What type of fixed resistor is made by applying a film or metal to a ceramic rod in a vacuum?
Proton Neutron Electron
What are the three principle parts of an atom?
resistance
What causes a wire to become warm when current flows through it?
Voltage
What is another term for electromotive force (EMF)?
tolerance
What is indicated by the fourth color band on a resistor?
metal oxide varistor
What is one device used for the spike suppression in either direct or alternating current circuits?
d'Arsonval movement
What is one of the most common analog meter movements? Moving coil meter is another name for the _______ meter movement.
8
What is the maximum number of valence electrons in an atom?
Magnetism
What is the most common method of producing electricity?
sine
What is the most common of all AC waveforms? Rotating machines normally produce a waveform called a _____ wave.
An atom
What is the smallest part of an element that still retains the properties of that element?
henry (H)
What is the unit of measurement for inductance?
Coulomb's Law
What law states that the force of electrostatic attraction or repulsion is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them?
one and three
A conductor is made from a material that contains between __________________ valence electrons.
analog
A test meter that uses a scale and pointer to indicate values is a(n) ______ meter.
15 A
A toaster is listed as 1800 W. When it is plugged into a 120 V circuit and starts to make toast, how many amperes will it draw?
rheostat
A variable resistor with two terminals is called a __________.
bidirectional
Alternate current is described as ______________.
True
T or F: Lightning is the result of static charges built up in clouds that contain a large amount of moisture.
true
T or F: The amount of voltage induced into a conductor depends on teh turns of wire, the strength of the magnetic field, and the speed of the cutting action.
True
T or F: The grounding conductor helps prevent a shock hazard in the event that an ungrounded, or hot, conductor comes in contact with the case or frame of an appliance.
True
T or F: The grounding prong of a plug should never be cut off or bypassed.
false
T or F: The north pole of a compass needed points in the direction of the south geographic pole.
False
T or F: There are many more resistance values available for ten percent tolerance resistors than for one percent tolerance resistors.
False
T or F: Voltage flows through an electric circuit like water flows through a pipe.
volt
The amount of potential necessary to cause one coulomb to produce one joule of work is a(n) ___________.
zero to the highest value obtained in either direction
The amplitude of a waveform is measured from ____.
Protons
The atomic number of an element is the number of _____ in the nucleus.
Ayrton shunt
The resistor are connected in parallel with the meter on some ranges and in series for other ranges when a ___ is used.
selenium
The semiconductor material used as a coating on copy drums is _______.
useful
The static charges sometimes used during sprat paining is an example of a(n) _____ static charge.
ampere turns
The strength of an electromagnet is primarily proportional to its ___.
electron
The theory concerning current flow that is most widely accepted as being correct is the ___________ flow theory.
spike
When the current flow through an inductor stops and the current also decreases at an exponential rate, a voltage ___ occurs.
thrust
When using the left-hand generator rule, the thumb points to the direction of the ____.