# plz help !!!!circuits

Discussion in 'Homework Help' started by kitibwa, Apr 22, 2008.

1. ### kitibwa Thread Starter New Member

Apr 10, 2008
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see attachment

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2. ### Caveman Active Member

Apr 15, 2008
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What's the deal? You have time for four exclamation marks, but not to type the details to your question? Type it out for cripes sake!

3. ### Dave Retired Moderator

Nov 17, 2003
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Can you scan the question and upload it as an attachment?

Dave

4. ### mik3 Senior Member

Feb 4, 2008
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It is just the graph of a cosine with t>0 but with double the frequency of an ordinary cosine graph. Also to amplitude is not from 1 to -1 but from 10 to -10.

5. ### Caveman Active Member

Apr 15, 2008
471
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That's what I thought, but then I noticed that he defined V(t), but asked for i(t).

6. ### mik3 Senior Member

Feb 4, 2008
4,846
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If the voltage is applied on a resistor, the current (i(t)) will have the phase as the voltage but divided by the resistors value.

If the voltage is applied to an inductor the current will lag the voltage waveform by 90 degrees, thus it will be a sine wave. Also divide by the reactance to find its amplitude.

If the voltage is applied to a capacitor the current will lead the voltage by 90 degrees, thus it will be a sinewave. Also divide by the reactance to find its amplitude.