1 Flashcards
1
Q
First discovered 2000 yrs ago by Greeks
A
Lodestone (magnetism) natural magnet
2
Q
Magnetic fields must oppose each other in these ways to demagnetize
A
Be struck hard, heat, reversing magnetic field
3
Q
The end of the magnet pointing to north and south are?
A
North Pole and South Pole
4
Q
What are the attraction and repulsion laws
A
Like poles repel, unlike poles attract
5
Q
____ __ _____ in a magnet extend out into space from the N pole to the S pole
A
Lines of force
6
Q
Left hand rule:
A
Thumb towards electron flow, fingers point towards magnetic field direction
7
Q
If # of loops are wound in same direction to form a coil, ____ _____ will add to make ____ _____ more dense.
A
More fields; flux lines
8
Q
A _______ _____ is used which has an extra set of contacts to keep current flowing through the relay even after the main switch is released.
A
Holding relay
9
Q
3 sections of transistors
A
Base, emitter, collector
10
Q
Whole circuits, manufactured with all components in place and ready to work are______ ______
A
Integrated circuits
11
Q
Two kinds of meme pry systems in common use are the ______ ______ ________ and the ____-_____ ______
A
Random access memory (temporary stored info); read- only memory (prearranged)
12
Q
Potential energy is most nearly associated with:
A
Force
13
Q
The accomplishment of a force acting through a distance is associated with:
A
Work
14
Q
Energy available for future use is called:
A
Potential
15
Q
The term “power” means:
A
Rate at which work is done
16
Q
Falling water contains:
A
Kinetic energy
17
Q
The acceleration of a freely falling body due to the force of gravity is :
A
32 ft/ second
18
Q
A foot lb is a unit of:
A
Work
19
Q
In 5 sec of fall, a falling body will fall a total of:
A
400 ft (d=1/2gt^2)
20
Q
The theoretical velocity of a freely falling body is equal to:
A
Square root of 2GH
21
Q
If the velocity of a stream of water is doubled the weight of a material it can suspend and carry is increased by:
A
16 times
22
Q
A pump raises 200 cubic ft of water to a height of 50 ft. How much was done to raise this water
A
624,000 ft lbs (200 x 62.4) x 50
23
Q
If the water in the above question is raised in 5 min. At what rate in horse power is the work done?
A
3.75
24
Q
Niagara falls is 160 ft high. At the top of the falls each cubic ft of water (62.4 lbs) has how many ft-lbs of potential energy
A
9984
25
Increasing the velocity of falling water will:
Increase available kinetic energy
26
Disregarding all other losses, rate of flow of a liquid is the product of:
Area x velocity
27
If the diameter of a pipe is decreased uniformly at its termination and with no change in pressure head, the exit velocity of the liquid is:
Increased
28
With continuous steady flow, the tota head at any point ina. Stream is equal to the total head at any downstream point plus the:
Loss of head between the two points
29
The sudden transformation within a pipe of the kinetic energy of the moving mass is water into pressure energy is the most usually associated with:
Water hammer
30
The damaging effects of water hammer can be controlled by:
Proper valve control, venting and print
31
All of the ______ _______ May be step up and step down windings, or some may be step up and some step down.
Secondary windings
32
Primary windings is ____ __ ___ _____ in the secondary times the number of turns in the secondary winding.
Equal to the current
33
The ____ ______ is a special type of iron core transfer which has one winding which serves as primary and secondary.
Auto transfer
34
I^R losses are called _____ _____.
Copper losses
35
____ ______ in a transfer core are reduced by dividing the core into many flat sections, or laminations that’s really insulated from each other
Eddy currents
36
The capacitance if a capacitor is determined by what three things
Surface area of the plates
The distance between plates
Insulating material (dielectric)
37
The capacitor voltage is often called a ____ ____ because it acts 180 degrees out of phase with applied voltage
Counter voltage
38
Capacitive reactance is expressed in...
Ohms
39
Component vectors in the same direction can be added...
Arithmetically
40
The closer the current is to being in phase with the applied voltage, the more what?
Resistance
41
Inductance ____ current
Leads
42
A vector has _____ and ____
Magnitude; direction
43
In and inductive circuit applied voltage ____ current by 90 degrees
Leads
44
In a capacitive circuit the current ____ applied voltage by 90 degrees
Leads
45
Multiplying apparent power by the cosine of the phase angle between voltage and current
True power
46
Like current in a parallel RL circuit is equal to the ____ ___ of the currents in the resistive and inductive branches.
Vector sum
47
A ________ Shows the magnitude and direction of the current or voltage at every incident of time
Waveform
48
The effective value is also called the ____ ____ ______ or rms value
Route mean square
49
The ____ Consumed in any circuit depends on the voltage and current in the circuit
Power
50
The two reasons for an increase in resistance are
When an ac current flows in a conductor
| It causes voltages to be set up inside of the conductor
51
The magnitude of the ____ at any instant is directly proportional to the magnitude of the _____ at that instant and is inversely proportional to the value of resistance
Current; voltage
52
The magnitude of the induced emf is directly proportional to the _____ of the magnetic Field, the link of the conductor, and the speed at which the conductor moves through the magnetic field
Strength
53
The relationship between the induced EMF and the applied voltage that causes the current flow is such that the two voltages are always
180 degrees out of phase
54
Since the action of the induced emf is to oppose the applied voltage it is often called the ____ or ______ ___
Back; counter emf (cemf)
55
One factor that effects self induction is the ______ _____ of the conductor
Physical shape
56
Unit of inductance is
Henry
57
If an AC circuit has only resistance the voltage and current in the circuit are
In phase
58
What are the four functions of the gear system
Transmit positive force
change direction
change speed
increase and decrease Force
59
Electromagnetic circuit breaker uses the principle of ____ to open a circuit When too much current flows
Magnetism
60
When a compound is broken down into a small form
Molecule
61
A material substance made of like chemicals that unite chemically
Element
62
Material substance made of unlike chemicals that unite chemically
Compound
63
Which of the four elements listed is the lightest per unit of volume
Calcium
64
Which of the four elements listed is the lightest per atomic weight
Carbon
65
Water is a
Compound
66
When two or more atoms combine chemically the particle this formed is a
Molecule
67
A compound is formed when the atoms of two or more elements become
Chemically bonded
68
Our air (atmosphere) is composed by volume of
21% oxygen and 79% nitrogen
69
Atmospheric pressure at sea level is normally considered to be approximately
14.7 psi
70
When molecules are tightly bound they are in a
Solid state
71
Liquids offer a high resistance to any force tending to change their
Volume
72
A pound is a unit of
Force
73
A temp reading of 59 degrees F is equal to
```
C= 5/9(F-32)
F= 9/5 C+32
```
15 degrees C
74
A temp reading of 85 degrees C is equal to
```
C= 5/9(F-32)
F= 9/5 C+32
```
185 degrees F
75
Density is a ratio between mass and?
Volume
76
When the temp of a substance increases or the pressure is reduced the substance does what
Expands and becomes less dense
77
If an objects weight is 210 lbs and volume is 3.5 cu ft what is the density
60 ft^3
78
Water has a density of 62.4 lbs/ft^3. the volume of 1000 lbs of water is
16ft^3
79
What can be used to find the weight of objects which cannot be weighed on scales
Specific gravity
80
A piece of concrete weighs 400 lbs in air and 350lbs in water what is the specific gravity
Weight in air/ weight in air -weight in water
8
81
Specific weight most nearly means
Density
82
Atmospheric pressure is _____ at sea level
Greater
83
The term viscosity most nearly means?
Resistance to physical change
84
What is the pressure on the bottom of a discharge line at 200ft?
12,480lbs/ft^2
85
The pressure upward at any given point in a liquid is ____ the downward pressure at that point
The same as
86
A slanting penstock 2000ft king conveys water from a reservoir to a turbine 800ft below the level of the reservoir the pressure at the turbine would be?
800x62.4
49,920lbs/ft^2
87
What is the force on the bottom of a tank 6ftx8ftx12ft filled to a depth of 3ft with water
8985.6lbs
88
How to get Gauge pressure to absolute pressure @sea level conditions
Add 14.7
89
The pressure against a large piston in a confined space is
Proportional to the area on a small piston
90
Fluid pressure might be expressed properly by?
Lbs/in^2
91
The forces that are req’d to move fluid through a siphon are:
Friction head and static head
92
If you need to measure with accuracy greater than hundredth of in. You use a?
Vermiar caliper
93
What tool can measure inside and outside diameters if a pipe
Slide caliper
94
If a micrometer is graduated in inches how far does spindle move in one revolution
1/40 in.
95
Which head is used on combo square for measuring any size angles
Protractor
96
Wrenches made of ________ steel are lightweight
Chrome-vandium
97
Distance across flate on a volt head usually equal diameter times what
1 1/2
98
The type of socket handle that provides most leverage for breaking loose very tight nuts
Hinges drive lug
99
Best wrench for removing a “frozen” nut from bolt
Strike-face box
100
Whole tip of a _____ screwdriver fits into screwdriver
Phillips
101
Strap wrench is best for _____
Turning polished metal or plastic pipes
102
If you let the back of hook jaw if pipe Wrench touch the pipe the gripping action will be
Reduced
103
When tracking a pipe you should make how many turns
1
104
What tool is used to cut threads on inside of pipe fitting
Tap
105
One of the most important rules of two maintenance is to
Replace anyone worn parts
106
A typical plumbing system supplies water any pressure of
25,60
107
PVC pipes are used to drain waste and vent piping because they do not corrode and
Cut and join
108
You should plug the overflow opening in the sink before you use a
Force-cup plunger
109
A trap spoon is for
Guiding an auger
110
When installing pipe in a very narrow space such as between a sink and will use a
Basin wrench
111
What source should you primarily follow for specifications on electrical work
National electric code
112
What do you use for pulling electrical wire through conduit
Fish tape
113
Diagonal piers have?
Cutting jaws an angle to the handles
114
If you need to start a screw in a hard to reach area use a
Split tip
115
Use a neon circuit tester for
Testing for grounded electrical outlets
116
A ripsaw usually has ___ points/in.
4;8
117
A block plane is best for
Cutting the end grain of wood
118
Which part of an auger bit chips the wood
Lips
119
A forstner bit is especially useful for drilling a hole with?
With a flat bottom
120
Plumb is the ______ of a surface
Vertical trueness
121
Portland cement needs____ to harden
Moisture
122
A mixture of lime ,Portland cement and a few other things make what
Mortar
123
Hollowing the mortar bed with laying brick does what
Produces a firm bond with the brick
124
A ball float is a ____ tool
Smoothing
125
Glazing tools are used for cutting and installing what
Glass window panes
126
Gauge number tells you the size and what
Thickness
127
Three types of punches you can use to cut holes in sheet metal are the
Hollow, lever, solid
128
The color of the grips on a pair of aviation ships indicate the
Shape it will cut
129
Which level steak shown is bevel hedge square stake
B
130
In soldering the alloy that joins two pieces of metal has a melting point
Lower then
131
A vise tool is used for
Holding
132
A “cut” of a file is the
Shape;set
133
When filing in which direction should you press downward
On the forward stroke
134
The thread diameter of a top should be measured with a
Screw thread micrometer
135
What thread class do most belt screws instead of regular quality have
Class two
136
Manila rope is made from long fibers of
Hemp
137
How can you prevent the end of the fiber rope from unraveling
With it with a cord
138
You cannot tie a knot in a rope made of what
Wire
139
Stainless steel ropes are well-suited to marine and indicate applications because of its?
Resistance to corrosion
140
Pullers that apply an impact rather than a steady force are called ______ pullers
Slide hammer
141
Capacitance is the electrical property which opposes any change in the?
Applied voltage
142
Inductance is that property which ____ any change in the current flow or in the magnetic field of an electric circuit
Opposes
143
The induced voltage that opposes the original emf applied to the circuit is called
Counter emf
144
Where the effects of inductance are noted within the same circuit where the original current exists is called
Self inductance
145
Hysteresis loss is most nearly associated with _______ repeatedly magnetizing and demagnetizing on AC magnetic core
Heat
146
Inductive reactance is present in ________ if a coil forms in a point of the circuit
AC circuits
147
Magnetic flux in a magnetic circuit has a relation similar to what expression appearing in ohms law
Current
148
The total flux in a circuit divided by the cross sectional area of the circuit path ends is what
Magnetic flux
149
The electron theory of magnetism assumes that magnetic action is due to:
The electron movement and arrangement of the electron orbits
150
The strength of an electromagnetic field is not affected by the:
Type of insulation
151
Permeability is the opposite of:
Magnetic reluctance
152
When a magnetic substance has reached the saturation point, it’s magnetic field
Cannot be increased
153
The polarity of an electromagnet will depend upon the
Direction of current flow through the coil
154
To induce a voltage across a solenoid, there must be
A change in the field cutting the coil
155
An induced voltage will not be created when:
A solenoid remains stationary within fixed field
156
Capacitance is that electrical property which opposes any change in the:
Applied voltage
157
Resistance of the load is ____ ______ than resistance of circuit wiring
Much greater
158
Every power source has some :
Internal resistance
159
Only way to decrease current and add resistor is by?
Increasing voltage source, load, or connecting wires
160
Resistors are usually made of?
Carbon
161
Resistors marked with a _____ show the range for variation
Tolerance
162
Resistors current rating usually in what rating?
Watt
163
Three things that resistors are composed of
Small
Rugged
Low cost
164
When all three terminals are connected into a circuit the resistor is called?
Potentiometer
165
When only the center terminal and one other terminal are used in a circuit it is a?
Rheostat
166
If E goes up I will go?
Up
167
If R goes down I will go?
Up
168
When calculating current, point out?
Knowns and unknowns
169
Power is amount of____ ____ by a kid in some point of time. (Usually 1 sec.)
Work done
170
A watt is the power used when?
1 amp of current flows through a potential difference of 1 volt.
171
An electrical circuit consists of what three things
1. Power source
2. Connecting wires or conductors
3. A device that uses electrical energy of the source to accomplish some purpose(load)
172
All switches perform the same basic function of what?
Opening and closing electrical circuits
173
Emf is measured in?
Volts
174
Amount of voltage supplied by the source determines?
How much current will flow
175
What 2 factors determine how much current flow in a DC circuit
1. Amount of voltage supplied by the power source
| 2. How well the load and the wires conduct current
176
Conductance is the ease in which metal?
Allows current to flow
177
Resistance of any material depends on # of free electrons and?
The longer the wire, the more resistance
178
In any circuit, current flows from ?
Neg to pos terminal
179
Power consumed in ac circuit is?
Ac power
180
Heat or power loss can be reduced by lowering what?
Either current carried by transmission or resistance or both
181
If resistance was doubled, _____ ____ would be doubled
Power loss
182
If current is doubled, power loss would?
Quadruple
183
What is the best way to lower power loss
Lower the current
184
The value of the power after the conversion is the same as its?
Value before conversion
185
A _____ shows magnitude and direction of the current or voltage at every instant in time
Waveform
186
The polarity and magnitude of a dc current or voltage?
Never change
187
Frequency is measured in?
Hertz
188
If the resistor fails by ______ or ______ it is usually because of the heat generated by the circuit
Burning out
| Value changes
189
Control bus batteries are used to supply electrical power to:
Emergency lighting systems, emergency pumps, operate oil circuit breakers.
190
The dry cell battery is a:
Primary cell
191
One essential difference between primary and secondary cells are that?
A secondary cell can be recharged
192
The plates of a lead acid battery are made of?
Lead and lead peroxide
193
A battery is receiving a normal charge. It begins to gas freely. The charging current should be?
Decreased
194
The # of neg plates in a lead acid cell is?
One greater than the # of pos plates
195
The ______ ______ of a battery refers to the charging rate in amps when the current just balances the current req’d by the external losses of the battery
Floating charge
196
A battery is on charge. An increase in the rate of ______ means, cell voltages are approaching 2.07v specific gravity of electrolyte is approaching 1.210, charging should be lowered.
Gassing
197
Which of the following best defines a cycle?
Two alternations
198
How many times larger is the maximum voltage value than the effective voltage value?
1.414
199
An AC voltmeter indicates that the effective voltage between two conductors in a cable is 440 volts. How many times during each cycle is the insulation subjected to maximum voltage stress?
2
200
The magnitude of a vector is denoted by the?
Length of line, drawn to scale
201
Direction of a simple vector is indicated by?
An arrow at one end
202
In the mathematical development of the wines of angles greater than 180 degrees correspond with those in the top half of the circle except that?
They have a minus sign and must be plotted below the base line
203
The effective value of an ac voltage or current of sine wave form is defined in terms of the equivalent dc?
Heating effect
204
Root means squared value is known as the?
Effective value
205
Most ac voltmeters and ammeters are calibrated in?
Rms values
206
Position rotation of a vector is?
Counterclockwise
207
The maximum value of a single sine wave of ac voltage is 141.4 volts. What is the effective value?
99.97 volts
208
When frequency is increased in a ac inductive circuit, the current flow will?
Decrease because of greater inductive voltage
209
The unit of measurement for reactive power is the?
Volt-amp-reactive (VAR)
210
The prime factors that determine inductive reactance are?
Inductance and frequency
211
What are the prime factors affecting capacitive reactance?
Frequency and capacitance
212
What is the opposition to current flow in an ac circuit created by resistance and reactances.
Impedance
213
In capacitive reactance, C represents capacitance in?
Farads
214
The phase angle between current and voltage in a circuit containing both resistance and inductive reactance is?
Greater than 0 but less than 90 degrees
215
What is the phase relationship between current and voltage in a pure capacitive circuit?
Voltage lags current by 90 degrees
216
Voltage and current are considered to be out of phase with each other in a pure inductive circuit by what amount?
Current lags voltage by 90 degrees
217
A device ____ which is the spring released coil, when energized, releases the charged ACB ______ spring to close the ACB
SRC; closing
218
There are disconnect couplers on either side of the ACB showing this to be a ____ ___ type of ACB
Rack out
219
Doubling the length of a conductor doubled its resistance and doubling its ___________ ____ reduces its resistance by one half.
Cross sectional area
220
Wherever the direction of current flow is mentioned, it shall be taken to mean the flow of current from a _____ point to a _____ point
Negative; positive
221
Capacitance is the electrical property which opposes any change in _____ and Inductance is the property that opposes any change in _____
Voltage; current
222
Capacitive reactance is the _______ offered by a capacitance to the flow of ______ ______ through a capacitor.
Opposition; alternating current
223
The charging current since it leads the voltage tends to make the _____ _____ of the system leading
Power factor
224
The effective values of voltage and of current are equal to the maximum values multiplied by?
0.707
225
A vector quantity may be represented by a directed ____ _____
Like segment
226
The positive direction of rotation is?
Counterclockwise
227
Power factor may also be described as the____ __ ___ _____ to apparent power
Ratio of true power
228
Secondary cells are those in which the chemical change can be ______ to restore the cell charge
Reversed
229
The active pets of the lead storage cell are the negative plate containing _____ ____ and the positive plate containing _____ _______
Sponge lead; lead peroxide
230
In cathodic protection the positive lead from the dc source is grounded near the pipe system to form an _____ and the negative lead is tied to the pipe line.
Anode
