Effective Voltage Calculation for Inductance Problem

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Homework Help Overview

The problem involves calculating the effective voltage between two points in an inductance scenario, with a focus on the behavior of current over time. The original poster expresses uncertainty about how to approach this type of problem, particularly in applying the relevant formula.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the application of the formula for mutual inductance and the interpretation of voltage values derived from current changes. There are questions about the directionality of the voltage and how to plot the voltage waveform to find the effective value.

Discussion Status

The discussion is ongoing, with some participants providing guidance on the interpretation of the formula and the significance of the inductor's orientation. There is acknowledgment of the original poster's attempts, but no consensus on a complete solution has been reached.

Contextual Notes

There is mention of the original poster's lack of familiarity with this type of problem, and a request for more detailed attempts to clarify their reasoning. The discussion includes references to plotting voltage waveforms and finding the root mean square (rms) value, indicating a focus on effective voltage calculations.

crom1
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Homework Statement


Find effective value of voltage between points 3 and 4. The diagram on the right shows behaviour of current i.

Homework Equations


[/B]
$$ u_M= M \frac{di}{dt} $$

The Attempt at a Solution

[/B]
I tried with formula above, didn't work for me. I haven't seen how to solve these kind of problems, so can someone give me a direction or a hint?
 

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You need to show what you've tried, not just said you did. How are we to see where you might have gone wrong if we can't see what you've done? Give us some details.
 
I never seen this kind of problem before,so I am not sure what to do. If the above formula is supposed to be used, then on the first part of interval (where i is increasing) i get u_m=5V,and on the second part I get u_m=20V but I guess in different direction?
I am not sure what to do with them.
 
crom1 said:
i get u_m=5V,and on the second part I get u_m=20V but I guess in different direction?
I am not sure what to do with them.
Looks correct to me.
crom1 said:
Find effective value of voltage between points 3 and 4.
Plot the voltage waveform accordingly and find its effective value. Do you know the general formula for finding the rms value?
 
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crom1 said:
I never seen this kind of problem before,so I am not sure what to do. If the above formula is supposed to be used, then on the first part of interval (where i is increasing) i get u_m=5V,and on the second part I get u_m=20V but I guess in different direction?
I am not sure what to do with them.
You've got the right idea. the quantity ##dI/dt## is a signed quantity. So it'll determine the sign of the voltage at the output. The inductor "dots" are an indication of how the flux linkage between the inductors is oriented with regards to the ends of the inductors. By convention, an increasing current entering into the dot end of one inductor produces a potential across the other inductor which tries to increase the current flowing out of its dot end.

Presumably you're expected to plot the resulting voltage curve?
 
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Thanks to both of you. I only have to find effective value, and I get the right solution (10V).
 

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