(1) Which of the following takes place in an ac circuit? (Choose as many as appl
ID: 1789583 • Letter: #
Question
(1)
Which of the following takes place in an ac circuit? (Choose as many as apply)
(A) Electrons move through a circuit at nearly the speed of light. (B) Electrons drift
forward very slowly. (C) Electrons vibrate back and forth in place with no
appreciable movement. (D) A pulsating electric field travels through the circuit at
nearly the speed of light.
(2)Superconducting materials do not obey Ohm's law; when current flows through a
superconductor, there is no voltage drop across the superconductor. What is the
electrical power output when a current flows through a superconductor? (A) at least
100 watts (B) an infinite amount of power, which is why no current can be sent
through a superconductor (C) there is no power output (D) the number of watts of
er output equals the number of amperes in the current (E) There is not enough
information given to answer this question.
Thankyou.
Explanation / Answer
1)
A) not the business... in fact in a conductor, usually the electrons move though them at surprisingly low speeds.
It is false.
B) well... after my first statement, I must mark it. Not only forward, in any direction and in this case also backwards too. It also depends of current magnitude, but speeds can be no more than a very few inches per minute. (higher speeds maybe achieved in transmissions lines)
if it refers to "forward only", this is false, if it means "forward, regardless if backwards or not", it is true.
C) main features of AC.
True, 100% sure.
D) Here we talk about waves, that flows at light speed and it will have the same format of current. My doubt lives in pulsating: I believe it does not refer strictly to a square wave, in this case the statement is true, a sin shaped wave.
True.
2)
There is no power output. The basic Electrical formula here is Power = voltage x current
You state that it is a superconductor. A perfect (Or pretty damn close to perfect conductor.) So there would be no voltage across is but there is still a current.
Substituting in.
P=0*I
P=0W
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