Electric Current - Questions
Electric Current
If 10 coulombs of charge flows through a wire in 100 seconds, the current in the wire is
(A) 100A.
(B) 0.1A.
(C) 10A.
(D) 0.01A.
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What this question is about
If 10 coulombs of charge flows through a wire in 100 seconds, the current in the wire is
(A) 100A. --- No.
Divide one number by the other.
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If 10 coulombs of charge flows through a wire in 100 seconds, the current in the wire is
(B) 0.1A. --- Yes.
(10C)/(100s) = 0.1C/s = 0.1A
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If 10 coulombs of charge flows through a wire in 100 seconds, the current in the wire is
(C) 10A. --- No.
Divide by the time.
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If 10 coulombs of charge flows through a wire in 100 seconds, the current in the wire is
(D) 0.01A. --- No.
Divide one number by the other and check the decimal point.
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The amount of moveable charge in a few feet of metal wire is most likely to be
(A) a micro-coulomb.
(B) a few dozen coulombs.
(C) a milli-coulomb.
(D) ten thousand coulombs.
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The amount of moveable charge in a few feet of metal wire is most likely to be
(A) a micro-coulomb.
No. That would be a typical unbalanced static charge.
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The amount of moveable charge in a few feet of metal wire is most likely to be
(B) a few dozen coulombs.
No. That is how much might flow past in one second.
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The amount of moveable charge in a few feet of metal wire is most likely to be
(C) a milli-coulomb.
No. This is balanced charge, remember.
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The amount of moveable charge in a few feet of metal wire is most likely to be
(D) ten thousand coulombs.
Yes. A few grams of copper would have that much.
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The average speed with which electrons move through a typical current-carrying wire is
(A) a few millimeters per second.
(B) close to the speed of sound.
(C) close to the speed of light.
(D) zero.
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The average speed with which electrons move through a typical current-carrying wire is
(A) a few millimeters per second.
Yes. For 10A thru a 1mm diameter wire.
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The average speed with which electrons move through a typical current-carrying wire is
(B) close to the speed of sound.
No. Electrons do not leave tiny little sonic booms.
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The average speed with which electrons move through a typical current-carrying wire is
(C) close to the speed of light.
No. Remeber, there is a lot of moveable charge in a wire.
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The average speed with which electrons move through a typical current-carrying wire is
(D) zero.
No. There would then be no current at all.
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The average speed with which a change in electric potential moves through a wire is
(A) a few millimeters per second.
(B) close to the speed of sound.
(C) close to the speed of light.
(D) zero.
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The average speed with which a change in electric potential moves through a wire is
(A) a few millimeters per second.
No. Telephones and telegraphs would then be slower than mailing a letter.
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The average speed with which a change in electric potential moves through a wire is
(B) close to the speed of sound.
No. Sound has nothing to do with it.
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The average speed with which a change in electric potential moves through a wire is
(C) close to the speed of light.
Yes. An electromagnetic wave travels down the wire.
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The average speed with which a change in electric potential moves through a wire is
(D) zero.
No. Unless the wire is broken.
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