Engineering RLC Parallel Circuit: Solving for Current & Energy

AI Thread Summary
To calculate the current in an RLC parallel circuit, use formulas for resistors, inductors, and capacitors based on voltage and their respective reactances. The current for the inductor at time t=0 is provided, and to find the current at a different time, this initial value must be used. Energy stored in the inductor and capacitor can be calculated using the energy equations, but understanding AC equivalent circuits and reactances is crucial. It's emphasized that existing equations may not directly apply, requiring derivation based on fundamental physics principles. Mastery of these concepts is essential for solving unfamiliar circuit problems effectively.
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Homework Statement



See image

Homework Equations



.5Li2
.5Cv2

The Attempt at a Solution



How do I calculate the current for a circuit of this type? I am unable to find any examples in our text. Can I use the following formulas to solve for the current flowing through each component:

I(r) = V/R
I(L) = V/X(L)
I(C) = V/X(C)

Would it be possible to find the energy stored in each component at t = .4 s?

Or would it be okay to use the energy equations for the L and C, accordingly.
In this case, .5(100^2)10*10^-6 = 50mJ
 

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How do I calculate the current for a circuit of this type?
You are given the current.

You can use kirkoffs laws.
You also have some notes about finding equivalent impedences and/or reactances and so on.
You are expected to use that information to solve problems you have not seen before.
 
Simon Bridge said:
You are given the current.

You can use kirkoffs laws.
You also have some notes about finding equivalent impedences and/or reactances and so on.
You are expected to use that information to solve problems you have not seen before.

huh? I'm not sure what you mean by your last two sentences...

I need to find the current going into the inductor, I wasn't sure if I was supposed to use the I(L) in order to find tat.
 
The problem statement you provided in the attachment does not tell you to find the current ... you are given the current for the inductor at t=0.
To find the current at another time, you will need to use this value.

huh? I'm not sure what you mean by your last two sentences...
... let me clarify:

When you said:
I am unable to find any examples in our text.
- this means that this is a problem you have not seen before. You are expected to be able to use knowledge you learn in your coursework to solve problems you have not seen before.

You asked about how to find currents and stored energy for a circuit like that.
How do I calculate the current for a circuit of this type?...
Would it be possible to find the energy stored in each component...
To do that, you have to use your understanding of AC equivalent circuits, reactances, and impedences.
You should have some notes in your coursework, and in the textbook, about these things already.

I want to get you off trying to find an existing equation and on to using your understanding of physics.
Chances are you don't have an equation to cover exactly this circuit - so you'll have to derive one.
 
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I will give it a try and take a look at it. My mind turns into spaghetti after looking at this stuff too long! My apologies for the confusion.
 

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