Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
64 Cards in this Set
- Front
- Back
|
What is matter, and in what three states is it found?
|
Matter is anything that occupies space and has weight. It is found as solid, liquid or gas.
|
|
|
What is an element?
|
An element is a substance that cannot be reduced to a simpler substance by chemical means.
|
|
|
What is a compound?
|
A compound is a substance consisting of two or more elements.
|
|
|
What is the difference between a compound or a mixture?
|
A compound is a chemical combination of elements that cannot be separated by physical means. A mixture is a physical combination of elements and compounds that are not chemically combined.
|
|
|
What is a molecule?
|
A molecule is the chemical combination of two or more atoms.
|
|
|
What are the three types of subatomic particles, and what are their charges?
|
The three types of subatomic particles and their charges are: electrons-negative, protons-positive, and neutrons-neutral.
|
|
|
What is energy of motion called?
|
Energy of motion is called kinetic energy.
|
|
|
How is invisible light changed to visible light in a fluorescent light?
|
Invisible light is changed to visible light in a fluorescent light when invisible light photons (ultraviolet) bombard the phosphor atom in the light tube. The phosphor atoms then emit visible light photons.
|
|
|
What determines the valence of an atom?
|
An atom's valence is determined by the number of electrons in the atom's outer shell.
|
|
|
What is an ion?
|
An ion is an atom with more or less electrons than it's normal number.
|
|
|
What determines whether a substance is a conductor or an insulator?
|
A substance is a conductor or insulator depending on the number of valence electrons.
|
|
|
How is a negative charge created in a neutral body?
|
A negative charge is created in a neutral body through the accumulation of excess electrons.
|
|
|
How are static charges created?
|
Static charges are created through friction.
|
|
|
What is the electrical charge of an atom which contains 8 photons and 11 electrons?
|
The electrical charge of an atom with 8 photons and 11 electrons is negative.
|
|
|
What is the relationship between charged bodies?
|
Like charges repel, unlike charges attract with a force directly proportional to the product of their charges ad inversely proportional to the square of the distance between them.
|
|
|
What is an electrostatic field?
|
An electrostatic field is the space between and around charged bodies.
|
|
|
In what direction are electrostatic lines of force drawn?
|
Electrostatic lines of force are always drawn from positive to negative.
|
|
|
What are some examples of electrical equipment which use magnetism?
|
Motors, generators, speakers, computers, and televisions are all examples of electrical equipment which uses magnetism.
|
|
|
What are magnetic materials?
|
Those materials that are attracted by magnets and have the ability to be magnetized.
|
|
|
What characteristics do all ferromagnetic materials have in common?
|
The relative ease with which they can be magnetized.
|
|
|
What type of magnetic material should be used to make a temporary magnet?
|
A material that offers low resistance and high permeability, such as iron or soft steel.
|
|
|
What is retentivity?
|
The ability of a material to retain magnetism.
|
|
|
How does the law of magnetic poles relate to the law of electric charges?
|
They are very similar; like charges repel, unlike charges attract, like poles repel--unlike charges attract.
|
|
|
A compass is located at the geographical North Pole. In which direction would it's needle point?
|
To the magnetic north pole.
|
|
|
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.
|
|
|
What is the difference between the domain theory and Weber's theory of magnetism?
|
The domain theory is based on the electron spin principle; Weber's theory uses the concept of tiny molecular magnets.
|
|
|
Imagine a bar magnet with a glass plate placed over it. For what purpose would you sprinkle iron filings on the glass plate?
|
To enable you to "see" the magnetic field.
|
|
|
Imagine a bar magnet with a glass plate placed over it. What pattern would be formed if sawdust was sprinkled on the glass instead of iron filings?
|
There would be no specific patterns as sawdust is a non-magnetic material.
|
|
|
What is a magnetic line of force?
|
An imaginary line used to illustrate magnetic effects.
|
|
|
In what way do magnetic lines of force differ from electrostatic lines of force?
|
Electrostatic lines of force do not form closed loops.
|
|
|
How should a delicate instrument be protected from a magnetic field?
|
By shielding or surrounding the instrument with a soft iron case, called a magnetic shield or screen.
|
|
|
How should bar magnets be stored?
|
In pairs, with opposite poles together to provide a complete path for magnetic flux.
|
|
|
What is the definition of energy?
|
The ability to do work.
|
|
|
What type of energy does a rolling stone have?
|
Kinetic energy.
|
|
|
What kind of energy does the stone have if it is at rest at the top of a hill?
|
Potential energy.
|
|
|
What term describes voltage or emf?
|
Difference of potential.
|
|
|
Convert 2.1 kV to volts.
|
2,100 volts.
|
|
|
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) µV.
|
|
|
A device which supplies a voltage is commonly referred to by what name?
|
A voltage source.
|
|
|
Name the six methods of producing a voltage.
|
Friction, pressure, heat, light, chemical action, and magnetism.
|
|
|
The piezoelectric effect is an example of a voltage being produced by what method?
|
Pressure.
|
|
|
A thermocouple is a device that produces voltage by what method?
|
Heat.
|
|
|
A battery uses what method to produce a voltage?
|
Chemical action.
|
|
|
A generator uses what method to produce a voltage?
|
Magnetic.
|
|
|
According to electron theory, an electric current flows from what potential to what potential?
|
Electron theory assumes that electron flow is from negative to positive.
|
|
|
The effects of directed drift take place at what rate of speed?
|
The speed of light (186,000 miles per second, 300,000,000 meters per second).
|
|
|
What is the relationship of current to voltage in a circuit?
|
Current increases as voltage increases.
|
|
|
Convert 350 mA to amperes.
|
0.35 amperes.
|
|
|
What is the symbol for ohm?
|
Ω
|
|
|
When would silver be used as a conductor in preference to copper?
|
When the need for conductivity is great enough to justify the additional expense.
|
|
|
Which wire has the least resistance? Wire A--copper, 1,000 circular mils, 6 inches long. Wire B--copper, 2,000 circular mils, 11 inches long.
|
Wire B.
|
|
|
Which temperature coefficient indicates a material whose resistance increases as temperature increases?
|
Positive.
|
|
|
What term describes a material whose resistance remains relatively constant with changes in temperature?
|
Zero temperature coefficient.
|
|
|
What is the unit of conductance and what other term is sometimes used?
|
The mho (G); siemens (S).
|
|
|
What is the relationship between conductance and resistance?
|
They are reciprocals of each other.
|
|
|
What is the schematic symbol for a resistor?
|
---/\/\/\---
|
|
|
What does the wattage rating of a resistor indicate?
|
Its ability to disipate heat.
|
|
|
What are the two disadvantages of carbon-type resistors?
|
1. Change value with age.
2. Limited power capacity. |
|
|
What type of resistor should be used to overcome the disadvantages of the carbon resistor?
|
The wire wound resistor.
|
|
|
Describe the differences between the rheostat connections and those of the potentiometer.
|
The rheostat may have two connections, one fixed and one moveable; the potentiometer always has three connections, one moveable and two fixed.
|
|
|
Which type of variable resistor should you select for controlling a large amount of current?
|
The rheostat.
|
|
|
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, blac, and gold.
|
|
|
A carbon resistor has the following color bands: The first band is yellow, followed by violeet, yellow, and silver. What is the ohmic value of the resistor?
|
470,000 ohms (470kohms).
|
|
|
A carbon resistor has a fifth color band of yellow. What does this signify?
|
The resistor's chance of failure is 0.001 percent for 1,000 hours of operation.
|
