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1 | |
Electric current originates from which part of an atom? |
| | A) | nucleus |
| | B) | positively charged protons |
| | C) | negatively charged electrons |
| | D) | entire atom acting as a unit |
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2 | |
Which of the following is true of electrical forces? |
| | A) | Electrical forces are produced by electrical charges. |
| | B) | Like charges attract, unlike charges repel. |
| | C) | Electrical forces are weaker than gravitational forces. |
| | D) | Positive and negative charges can combine to produce a third type of charge. |
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3 | |
How can electric charge be established? |
| | A) | Electrons can be removed from atoms and accumulated to produce a negative charge. |
| | B) | Atoms from which electrons have been removed produce positive electric charge. |
| | C) | Both A and B. |
| | D) | Neither A nor B. |
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4 | |
When a person combs her hair, static electricity is sometimes generated by what process? |
| | A) | Contact between the comb and hair results in a charge. |
| | B) | Friction between the comb and hair transfers electrons. |
| | C) | Deduction between the comb and hair. |
| | D) | Induction between the comb and hair. |
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5 | |
Which of the following is not an electrical classification of materials? |
| | A) | Conductors, which have electrons that move freely. |
| | B) | Insulators, whose electrons essentially do not move between atoms. |
| | C) | Semi-insulators, which sometimes conduct and sometimes insulate. |
| | D) | Semiconductors, which sometimes conduct and sometimes insulate. |
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6 | |
Coulomb's law relates charge and distance between interacting charged bodies, describing the electrical force as being |
| | A) | proportional to the sum of the charge. |
| | B) | inversely proportional to the distance between charges. |
| | C) | proportional to the product of the charges and inversely proportional to the distance. |
| | D) | proportional to the product of the charges and inversely proportional to the distance squared. |
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7 | |
Electrical as well as gravitational effects can be thought to be caused by fields. Which of the following is true of an electrical or gravitational field? |
| | A) | The field concept is often used to describe contact forces. |
| | B) | A gravitational or electrical field does not always exist in the space around an object. |
| | C) | Fields are useful for understanding forces acting through a distance. |
| | D) | There is no way to verify the existence of a force field since it is just a concept. |
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8 | |
Electrical voltage is a measure of |
| | A) | total amount of current. |
| | B) | how much current is moving through a circuit. |
| | C) | the ratio of work done moving electric charges. |
| | D) | how many electrons are moving through a wire. |
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9 | |
Which of the following is a description of electrical current? |
| | A) | The flow of electric charge through a material. |
| | B) | The electric potential between two points in a circuit. |
| | C) | The flow of protons through a material. |
| | D) | The movement of resistance. |
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10 | |
What is required to produce a sustained electric current? |
| | A) | A source of energy that moves charges. |
| | B) | A voltage source. |
| | C) | An electric field moving through a conductor. |
| | D) | Any of the above. |
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11 | |
What are the basic components of a simple electric circuit? |
| | A) | energy source, device where work is done, and switch |
| | B) | energy source, connecting wires, and switch |
| | C) | connecting wires, device, and switch |
| | D) | energy source, device where work is done, wires, and switch |
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12 | |
What is the definition of electric current? A flow of |
| | A) | electric charge in units of volts per s. |
| | B) | electric charge in units of coulomb per s. |
| | C) | electrons in units of electrons per s. |
| | D) | protons in units of protons per s. |
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13 | |
Which of the following is not a valid conclusion about electric current in a conductor? |
| | A) | Electric charges move because of an electric field throughout a circuit. |
| | B) | The electric field is produced by a source of energy that moves charges. |
| | C) | The electric field is established at near the speed of light in a circuit. |
| | D) | Electrons move very fast in response to the electric field. |
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14 | |
What is the meaning of the term "resistance" as applied to electricity? Resistance is a measure of a material's opposition to |
| | A) | voltage. |
| | B) | movement of protons. |
| | C) | current. |
| | D) | electric force. |
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15 | |
The units for electrical resistance are |
| | A) | ohms, which are equal to volts/amp. |
| | B) | ohms, which are equal to amps/volt. |
| | C) | newtons, which are electrically equal to ohms. |
| | D) | coulombs, which become ohms/volt for circuits. |
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16 | |
Ohm's law states which relationship between electrical quantities? |
| | A) | volts = current divided by amps |
| | B) | volts = current times resistance |
| | C) | volts = resistance times charge |
| | D) | volts = coulombs divided by charge |
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17 | |
Which of the following will have power units? |
| | A) | volts x amps |
| | B) | volts x ohms |
| | C) | volts x coulombs |
| | D) | volts x watts |
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18 | |
Electric power measures the rate at which electric work is performed and has the unit joules/second. How could total energy consumed during some time interval be determined from power? |
| | A) | energy = power/time |
| | B) | energy = time/power |
| | C) | energy = power + time |
| | D) | energy = power x time |
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19 | |
Which of the following is not a similarity between magnets and electrical charges? |
| | A) | There are attractive and repelling forces between unlike or like poles or charges. |
| | B) | Both magnets and electrical charges establish fields. |
| | C) | Both exert forces at a distance. |
| | D) | Both magnetic poles and electric charges can be separated. |
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20 | |
Magnetic fields can be created by which process? |
| | A) | The motion of isolated magnetic poles. |
| | B) | The motion of electrons. |
| | C) | Static electric charge in a piece of iron. |
| | D) | The space around an electron. |
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21 | |
An electric field can be created by which process? |
| | A) | The motion of a magnetic field. |
| | B) | The motion of electrons. |
| | C) | Moving charges in a conductor. |
| | D) | Stationary magnet and wire. |
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22 | |
Which of the following will not strengthen the magnetic field produced by a single straight current carrying wire? |
| | A) | Coiling the wire. |
| | B) | Increasing the current. |
| | C) | Coiling the wire around a piece of iron. |
| | D) | Increasing wire thickness. |
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23 | |
An electric motor can be understood in terms of what kind of energy conversion? |
| | A) | mechanical energy to electrical energy |
| | B) | magnetic energy to electrical energy |
| | C) | electrical energy to mechanical energy |
| | D) | electrical energy to magnetic energy |
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24 | |
The basic mechanical action in a motor originates through which of the following? |
| | A) | forces between internal magnetic fields |
| | B) | forces between internal electric fields |
| | C) | both A and B |
| | D) | neither A nor B |
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25 | |
What energy conversion is accomplished by an electric generator? |
| | A) | electrical energy to mechanical energy |
| | B) | mechanical energy to electrical energy |
| | C) | steam energy to mechanical energy |
| | D) | electrical energy to nuclear energy |
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