Recent content by eng_stud

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    Initial conditions for rlc series natural response

    Homework Statement Find v(t) across a cap. in a series rlc circuit with no driving force (initial v across cap: 24V) Homework Equations from the values of the components, \alpha > \omega_0, the circuit is overdamped, and the following equation can be used: v(t) =A_1 e^{s_1 t} + A_2...
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    Source transformations doesn't always produce same result?

    Thanks, skeptic2!
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    Source transformations doesn't always produce same result?

    Follow-up question: If you have a circuit with a 10 A dc current source, with a 3 Ohm resistor and a 0.02 F capacitor in parallel, what determines the resulting voltage across the parallel setup? When the capacitor is fully charged? Or the voltage that would have been the source had we done a...
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    Source transformations doesn't always produce same result?

    I was under the impression that a source transformation doesn't change a circuit at all, which I guess is an oversimplification. If you have a series RC circuit, with a DC voltage source, after the transients have died out, all voltage will be across the capacitor, and none across the...
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    Complex impedance and negative reactance

    That makes sense, thank you!
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    Complex impedance and negative reactance

    Homework Statement consider a circuit expressed by v(t)= 100cos \omega t and i(t)=2cos(\omega t+\pi / 3) . Find the reactance.Homework Equations Z=\frac{V}{I} = R+jXThe Attempt at a Solution Z=\frac{100}{2\angle \pi /3} = 50\angle -\pi /3 = 46 - j19 Does the negative imaginary part mean...
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    Engineering Total Impedance of RL Circuit in Parallel with Resistor

    Homework Statement find total impedance of a circuit with R1 and L in parallel with R2. circuit looks like this (but with R2 instead of C): http://wpcontent.answcdn.com/wikipedia/en/thumb/7/75/RL_series_C_parallel.svg/160px-RL_series_C_parallel.svg.png Homework Equations formula for two...
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    Engineering Complex impedance of parallel RC circuit

    Thanks!
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    Engineering Complex impedance of parallel RC circuit

    In my book (Storey), there's an exercise with a parallel RC circuit, where R = 80 Ohm and C = 30 uF. The answer for the complex impedance is supposed to be 40-j40, however I can't seem to get there! I've showed my working under. Am I doing something wrong, or is the book's answer wrong? (freq...
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    Why is there a 90 degree phase shift in RC filters?

    Thank you! That made things very clear. While we're on it, is there by the way a simple explanation as to why the current leads the voltage by exactly 90 degrees, and not any at any other arbitrary phase angle?
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    Why is there a 90 degree phase shift in RC filters?

    That makes sense, yes! But in the extreme case with no resistor, and source voltage and output voltage across capacitor in phase, is the current then 90 degrees out of phase with both? (since it must be 90 degrees out of phase with the voltage across the capacitor) ? Thank you for your...
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    Why is there a 90 degree phase shift in RC filters?

    Thank you vk6kro, that makes sense! Follow-up question: How is it that in when the frequency is low, and most voltage is across the capacitor, the phase shift is approaching zero and we effectively have a real voltage (while imaginary if the frequency is high and most voltage is across the...
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    Why is there a 90 degree phase shift in RC filters?

    Hi! Bear with me: When the frequency is low in an RC series circuit and we take the voltage across the capacitor, the capacitors reactance is high and thus most voltage is across it. But when the frequency is high, the reactance goes down, and little to no voltage is dropped across the...