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Violagirl
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Homework Statement
1. A 5.0 H inductor is connected to a 120 V rms, 60 Hz ac power supply. Periodically, the energy stored in the inductor reaches a maximum value. What is this maximum value?
A) 0.010 J B) 0.020 J C) 0.40 J D) 0.80 J E) 10.0 J
2. A standing wave on a string is represented by the equation y = A sin (kx) cos (ωt). The distance between consecutive nodes is:
A) ∏/k B) ∏/ω C) 2∏/k D) k/∏ E) ω/∏
The Attempt at a Solution
These were two questions from an exam I had today and I wanted to check to see if my thinking was correct? For the first question, I put C.
I first found the period, 1/f, and got 1/60 = .0167 sec.
Next, I divided the 120 V rms by 5 H and got an answer of 24 V/H. Finally, I multiplied the frequency into this value and got an answer of 0.40 J. Was this correct?
For number 2, I rationalized that a node corresponds to half of a wavelength, which is equivalent to pi. And I know that k is equal the number of wave peaks in a wave. Therefore, out of the choices possible, I thought that A made the most sense. If anyone could confirm whether or not that is correct, I would appreciate it.