What is the instantaneous value of UL after commutation?

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Homework Help Overview

The discussion revolves around finding the instantaneous value of UL after commutation in a circuit involving inductors and resistors. The participants are exploring the implications of commutation on circuit behavior, particularly focusing on the inductor's response during the transition between states.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the conditions before and after commutation, questioning the behavior of current and voltage across components like resistors and inductors. There are inquiries about the definitions and differences between classical and operator methods for solving the problem.

Discussion Status

The discussion is ongoing with various interpretations being explored. Some participants have offered insights into the behavior of inductors during commutation and the concept of Norton equivalents, while others are seeking clarification on the methods and the specific calculations needed for the problem.

Contextual Notes

There are mentions of potential confusion regarding the definitions of classical and operator methods, as well as the need to derive equivalent circuits for different states of the circuit. Some participants express uncertainty about the initial conditions and the role of the inductor before and after the switch is closed.

  • #61


gneill said:
l = 12

l=0.012
 
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  • #62


builder_user said:
l=0.012

If you say so. In your first post you had:

K1=1.2
L = 10*K1

You did not indicate units (for anything!) so I assumed Ohms for resistances and Henries for inductance.
 
  • #63


gneill said:
Thevenin equivalent circuit and wrote KVL around the loop.

This loop?
 

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  • #64


gneill said:
You did not indicate units (for anything!) so I assumed Ohms for resistances and Henries for inductance.

I forgot.In every task I have millihenries and so I've not written it there.
 
  • #65


builder_user said:
This loop?

No, this loop. All of the source and resistor network is replaced by its Thevenin equivalent. Makes life simple.
 

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  • #66


builder_user said:
I forgot.In every task I have millihenries and so I've not written it there.

Okay. Perhaps in future you should just state the component values. All the K multipliers and assumed units is confusing.
 
  • #67


gneill said:
No, this loop. All of the source and resistor network is replaced by its Thevenin equivalent. Makes life simple.

Thevenin equivalent after commutation?Or at the moment of commutation?One of the equivalents that was found before?Or not found in this topic?
 
  • #68


builder_user said:
Thevenin equivalent after commutation?Or at the moment of commutation?One of the equivalents that was found before?Or not found in this topic?

After the switch closes, so yes, after commutation.

The circuit at the moment the switch closes remains the same thereafter.

It's only the initial conditions (the existing current in the inductor) that makes the moment of commutation special.
 
  • #69


How to do inverse Laplace transform in MathCAD?
 
  • #70


builder_user said:
How to do inverse Laplace transform in MathCAD?

Select the 's' variable and then Symbolics --> Transform --> Inverse Laplace.
 
  • #71


Thanks.
 

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