AREA III - Farm Electrification Flashcards

1
Q

One of the most versatile and widely used forms of energy.

a. Wind
b. Electricity
c. Water
d. Geothermal

A

b. Electricity

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2
Q

Clouds driven by strong winds can gather huge electrostatic charges which are released to the earth in the form of lightning.

a. Chemical Action
b. Adiabatic reaction
c. Friction between moving objects
d. Cyclonic motion of objects

A

c. Friction between moving objects

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3
Q

Certain types of crystals produce a voltage when subjected to pressure.

a. Magnetism
b. Thermoelectricity
c. Photoelectricity
d. Piezoelectricity

A

d. Piezoelectricity

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4
Q

Voltage is produced when the junction of two unlike metals is heated.

a. Magnetism
b. Thermoelectricity
c. Photoelectricity
d. Piezoelectricity

A

b. Thermoelectricity

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5
Q

A material that uses the principle of thermoelectricity.

a. Thermal Conductors
b. Heat Insulator
c. Thermolinks
d. Thermocouples

A

d. Thermocouples

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6
Q

Solar or photo cells convert radiant energy to electrical energy.

a. Magnetism
b. Thermoelectricity
c. Photoelectricity
d. Piezoelectricity

A

c. Photoelectricity

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7
Q

Produces a voltage by operating on the principle of electromagnetic induction.

a. Magnetism
b. Thermoelectricity
c. Photoelectricity
d. Piezoelectricity

A

a. Magnetism

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8
Q

Smallest portion into which an element can be subdivided without losing its physical and chemical properties

a. Molecules
b. Atom
c. Carbon
d. Particle

A

b. Atom

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9
Q

Outermost electrons

a. Negatively-charged Electrons
b. Protons
c. Positively- charged Electrons
d. Valence Electrons

A

d. Valence electrons

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10
Q

if an object contains more number of total electrons than the total protons

A

Negatively charged

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11
Q

if an atom contains fewer number of total electrons than the total protons

A

Positively charged

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12
Q

the amount of electrical charge on a single electron

A

Elementary charge unit (ECU)

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13
Q

used to measure quantity of electric charge; approximately equal to 6.24 x 10^18 ECU.

A

Coulomb (C)

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14
Q

Defined as the rate at which electrical charge flows

a.
b.
c.
d.

A

Current

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15
Q

Causes electric charge to flow in an electrical system having potential difference

A

Electromotive force (emf)

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16
Q

Ability of a material to resist the flow of electrical charge when subjected to a given potential difference

A

Electrical Resistance

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17
Q

property of a material to oppose the flow of electric current

A

Resistivity

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18
Q

materials having an intermediate resistance to electron flow

A

Semiconductors

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19
Q

materials which has low resistance to electron flow

A

Conductors

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20
Q

materials which has high resistance to electron flow

A

Insulators

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21
Q

States that the current flowing in a circuit varies directly with the electrical pressure and inversely with the opposition

A

Ohm’s law

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22
Q

States that the sum of the current in a node must be equal to zero

A

Kirchhoff’s current law

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23
Q

The net voltage around a close circuit is zero

A

Kirchhoff’s voltage law

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24
Q

The common unit of electric power

A

Watt

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25
The common unit of electric resistance
Ohm
26
Power factor for electric motors
between 0.6 to 0.8
27
Power factor for heaters, electric ranges and incandescent lamps.
1
28
The common unit of electric energy consumption
watt-hour (Wh)
29
the voltage across each resistor is directly proportional to the ratio of its resistance to the total series resistance of the circuit
Voltage divider
30
the current divides in inverse proportion to the resistances of the individual parallel elements
Current divider
31
TRUE or FALSE. it is impossible to view a very complicated circuit in terms of much simpler equivalent source and load circuits
FALSE
32
States that any network composed of ideal voltage and current sources, and of linear resistors, may be represented by an equivalent circuit consisting of an ideal voltage source in series with an equivalent resistance.
Thevinin’s theorem
33
States that any network composed of ideal voltage and current sources, and of linear resistors, may be represented by an equivalent circuit consisting of an ideal current source in parallel with an equivalent resistance.
Norton’s theorem
34
Characterized by non-variant current flow in one direction at all times
Direct Current (DC)
35
Characterized by an alternating flow of in two directions
Alternating Current (AC)
36
When voltage and current are in phase, all the power is __________
Positive
37
It is “watt-less” and does no useful work.
Reactive power
38
property to oppose current change
Inductance
39
The amount of electric charge that a capacitor receives for each volt of applied potential
Capacitance
40
Power factor improvement can be accomplished on what way?
addition of series or parallel-connected capacitors.
41
This material had the ability to attract bits of iron.
lodestones (Fe3O4)
42
First magnets
magnetite or “lodestones” (Fe3O4)
43
lines of force surrounding a permanent magnet or a moving charged particle.
Magnetic fields
44
Quantity of magnetic field force or "push"; also known as magnetic potential difference
Magnetomotive force (mmf)
45
It is Analogous to electric voltage (emf).
Magnetomotive force (mmf)
46
quantity of total field effect or "substance" of the field; analogous to electric current.
Magnetic flux
47
amount of field force (mmf) distributed over the length of the electromagnet.
Magnetic field strength (intensity)
48
amount of magnetic field flux concentrated in a given area
Magnetic flux density
49
The opposition to magnetic field flux through a given volume of space or material
Reluctance
50
Measure of a material's acceptance of magnetic flux
Permeability
51
Describes that the electric field due to electric charges can be derived by Coulomb’s Law.
Gauss’s law for electricity
52
states that the net magnetic flux through any (real or imaginary) closed surface is zero.
Gauss’ law for magnetism
53
Describes the production of magnetic fields not only by electric currents but by changing electric field as well
Ampere’s law
54
Describes the production of electric fields as a result of changing magnetic fields
Faraday’s law of induction
55
Voltage induced by a changing magnetic flux
induced emf
56
current produced during electromagnetic induction
induced current
57
A generator that produces unidirectional current
DC generator
58
also called alternator, produces alternating current
AC generator
59
3-wire, 3-phase system will deliver how many times as much power as a 2-wire, single-phase system?
1.73 times
60
A device that transfers energy from one electric circuit to another without change in frequency and usually (but not always) with a change in voltage.
Transformer
61
The primary winding has more turns than the secondary.
Step-up transformer
62
The primary winding has fewer turns than the secondary.
Step-down transformer
63
States that the induced voltage in a coil is always in a direction so as to oppose the effect which is producing it.
Lenz’s law
64
Refers to the portion of electric conductors that extends from the service entrance to an outlet or a certain group of outlets.
Branch circuit
65
Type of branch circuit for table lamps, radios, television and other portable appliances.
Lighting and general-purpose circuits
66
Type of branch circuit for portable appliances in the kitchen, dining area and laundry.
Small appliance circuits
67
Type of branch circuit for ranges, air conditioners, water heaters, water pumps, furnaces, and dishwashers.
Special purpose circuits
68
Electrical conductors which are 8 mm2 (AWG No. 8) or smaller in size.
Wires
69
Electrical conductors which are larger than the wires.
Cables
70
Meaning of AWG
American Wire Gauge
71
1 mil is equal to how many inches?
0.001 in
72
It is useless for many actual calculations involving true area.
circular mil
73
Grounding of current-carrying portions of a system
System grounding
74
Grounding of equipment not intended to be at a voltage potential different from the earth
Equipment grounding
75
What is he resistance of the human body when dry?
about 500,000 Ω
76
What is he resistance of the human body when wet?
about 300 Ω
77
Amount of voltage can cause sufficient current to be fatal
30 V
78
the use of colors of conductor covers in the wiring connections
Polarizing
79
It is always the ‘neutral wire’
White wire
80
‘hot’ conductors
Red or black wires
81
Grounding wire
Green wire
82
Overcurrent devices of which a portion is destroyed when interrupting the circuit
Fuses
83
Device designed to open a circuit automatically on a predetermined overload current without damage to itself
circuit breaker
84
The best location for indoor type distribution center
Position closest to the equipment having the largest wattage rating
85
The best location for outdoor type distribution center
Nearest to the electrical load center
86
The best location for pole type distribution center
located at the electrical load center of the farmstead
87
Three criteria to consider for the selection of wires for feeder lines
(a) size to carry current. (b) size of wire to prevent excessive voltage drop (Allowable voltage drop = 2%). (c) type and location adapted to surroundings
88
It constitutes only a small portion of the electromagnetic spectrum
Light
89
It involves the procedure of dividing the room into zones.
zonal cavity method