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63 Cards in this Set
- Front
- Back
What is matter, and in what three states is it found?
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Matter is defined as anything that occupies space and has weight; SOLID, LIQUID, and
GASEOUS |
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What is an element?
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An ELEMENT is a substance which cannot be reduced to a simpler substance by chemical means
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What is a compound?
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A compound is a chemical combination of elements which can be separated by chemical
but not by physical means |
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What is the difference between a compound and a mixture?
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Compounds are chemically combined and cannot be seperated by physical means, while mixtures are not chemically combined and can be seperated by physical means.
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What is a molecule?
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A MOLECULE is a chemical combination of two or more atoms
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What are the three types of subatomic particles, and what are their charges?
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The atoms of each element are made up of electrons(negative), protons(positive), and, in most cases, neutrons(neutral), which are
collectively called subatomic particles. |
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What is energy of motion called?
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Energy of motion is called KINETIC ENERGY
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How is invisible light changed to visible light in a fluorescent light?
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This principle is used in the fluorescent light where ultraviolet light photons, which are not visible to
the human eye, bombard a phosphor coating on the inside of a glass tube. The phosphor electrons, in returning to their normal orbits, emit photons of light that are visible. |
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What determines the valence of an atom?
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The number of electrons in the outermost shell determines the valence of an atom.
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What is an ion?
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When the atom loses electrons or gains electrons in this process of electron exchange, it is said to be
IONIZED |
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What determines whether a substance is a conductor or an insulator?
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The number of valence electrons.
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How is a negative charge created in a neutral body?
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Through the accumulation of excess electrons.
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How are static charges created?
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By friction.
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What is the electrical charge of an atom which contains 8 protons and 11 electrons?
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Negative.
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What is the relationship between charged bodies?
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Like charges repel, and unlike charges attract with a force directly proportional to the product of
their charges and inversely proportional to the square of the distance between them. |
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What is an electrostatic field?
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The space between and around charged bodies.
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In what direction are electrostatic lines of force drawn?
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Leaving positive, entering negative.
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What are some examples of electrical equipment which use magnetism?
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Motors, generators, speakers, computers, televisions, tape recorders, and many others
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What are magnetic materials?
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Those materials that are attracted by magnets and have the ability to become magnetized
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What characteristics do all ferromagnetic materials have in common?
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The relative ease with which they are magnetized.
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What type of magnetic material should be used to make a temporary magnet?
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A material that exhibits low reluctance and high permeability, such as iron or soft steel.
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What is retentivity?
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The ability of a material to retain magnetism.
A23. They are very similar; like charges repel, unlike |
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How does the law of magnetic poles relate to the law of electric charges?
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They are very similar; like charges repel, unlike charges attract, like poles repel—unlike poles
attract. |
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A compass is located at the geographical North Pole. In which direction would its needle point?
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To the magnetic north pole.
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Using Weber's molecular theory of magnetism, describe the polarity of the magnetic poles
produced by stroking a magnetic material from right to left with the south pole of a magnet. |
South pole at the right, north pole at the left.
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What is the difference between the domain theory and Weber's theory of magnetism?
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The domain theory is based upon the electron spin principle; Weber,s theory uses the concept of
tiny molecular magnets. |
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What is a magnetic line of force?
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An imaginary line used to illustrate magnetic effects.
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In what way do magnetic lines of force differ from electrostatic lines of force?
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Electrostatic lines of force do not form closed loops.
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How should a delicate instrument be protected from a magnetic field?
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By shielding or surrounding the instrument with a soft iron case, called a magnetic shield or
screen. |
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How should bar magnets be stored?
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In pairs, with opposite poles together to provide a complete path for magnetic flux.
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What is the definition of energy?
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The ability to do work.
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What type of energy does a rolling stone have?
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Kinetic energy.
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What kind of energy does the stone have if it is at rest at the top of a hill?
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Potential energy.
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What term describes voltage or emf?
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Difference of potential.
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Convert 2.1 kV to volts.
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2100 volts.
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Express the following in more simple terms. (a) 250,000 volts, (b) 25,000,000 microvolts, (c)
0.001 millivolt. |
(a) 250 kV, (b) 25 V, (c) 1 μV.
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A device which supplies a voltage is commonly referred to by what name?
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A voltage source.
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Name the six methods of producing a voltage.
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Friction, pressure, heat, light, chemical action, and magnetism.
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The piezoelectric effect is an example of a voltage being produced by what method?
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Pressure.
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A thermocouple is a device that produces voltage by what method?
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Heat.
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A battery uses what method to produce a voltage?
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Chemical.
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A generator uses what method to produce a voltage?
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Magnetic.
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According to electron theory, an electric current flows from what potential to what potential?
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Electron theory assumes that electron flow is from negative to positive.
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The effects of directed drift take place at what rate of speed?
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The speed of light (186,000 miles per second, 300,000,000 meters per second).
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What is the relationship of current to voltage in a circuit?
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Current increases as voltage increases.
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Convert 350 mA to amperes.
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0.35 amperes.
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What is the symbol for ohm?
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Ω
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When would silver be used as a conductor in preference to copper?
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When the need for conductivity is great enough to justify the additional expense.
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Which wire has the least resistance? Wire A-copper, 1000 circular mils, 6 inches long. Wire
B-copper, 2000 circular mils, 11 inches long. |
Wire B.
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Which temperature coefficient indicates a material whose resistance increases as temperature
increases? |
Positive.
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What term describes a material whose resistance remains relatively constant with changes in
temperature? |
Zero temperature coefficient.
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What is the unit of conductance and what other term is sometimes used?
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The mho (v), siemens.
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What is the relationship between conductance and resistance?
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They are reciprocals of each other.
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What is schematic symbol for a resistor?
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-^^^-
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What does the wattage rating of a resistor indicate?
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Its ability to dissipate heat.
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What are the two disadvantages of carbon-type resistors?
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1. Change value with age. 2. Limited power capacity.
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What type resistor should be used to overcome the disadvantages of the carbon resistor?
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The wirewound resistor.
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Describe the differences between the rheostat connections and those of the potentiometer.
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The rheostat may have two connections, one fixed and one moveable; the potentiometer always
has three connections, one moveable and two fixed. |
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Which type of variable resistor should you select for controlling a large amount of current?
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The rheostat.
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A carbon resistor has a resistance of 50 ohms, and a tolerance of 5 percent. What are the colors of
bands one, two, three, and four, respectively? |
The bands are green, black, black, and gold.
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A carbon resistor has the following color bands: The first band is yellow, followed by violet,
yellow, and silver. What is the ohmic value of the resistor? |
470,000 ohms (470 kilohms).
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The same resistor mentioned in question 63 has a yellow fifth band. What does this signify?
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The resistor,s chance of failure is 0.001 percent for 1000 hours of operation.
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A resistor is handed to you for identification with the following color code: the first band is blue,
followed by gray, green, gold, and brown. What is the resistor,s value? |
6,800,000 ohms (6.8 megohms), with 5% tolerance, and a 1% reliability level.
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