Second Order Circuits: Difference between revisions

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'''Second order circuits''' are circuits that have two energy storage
'''Second order circuits''' are circuits that have two energy storage elements, resulting in second-order differential equations.
elements, resultingin second-order differential equations. There are
 
primarily two types:
There are primarily two types:


* Parallel RLC circuits
* Parallel RLC circuits
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== Unforced ==
== Unforced ==
[[File:Unforced RLC Circuit.png|thumb|An unforced RLC circuit]]
[[File:Unforced RLC Circuit.png|thumb|An unforced series RLC circuit]]
Consider an un-forced RLC circuit. We want to find <math>V_C</math>.
Consider an un-forced RLC circuit. We want to find <math>V_C</math>.


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<math>\frac{d^2V_C}{dt^2} + \frac{R}{L} \frac{dV_C}{dt} + \frac{1}{LC} V_C = 0</math>
<math>\frac{d^2V_C}{dt^2} + \frac{R}{L} \frac{dV_C}{dt} + \frac{1}{LC} V_C = 0</math>


= Parallel RLC Circuits =
== Unforced ==
[[File:Parallel Unforced RLC Circuit.png|thumb|A parallel unforced RLC circuit]]
[[Category:Electrical Engineering]]
[[Category:Electrical Engineering]]

Revision as of 06:54, 8 March 2024

Second order circuits are circuits that have two energy storage elements, resulting in second-order differential equations.

There are primarily two types:

  • Parallel RLC circuits
  • Series RLC circuits

Series RLC Circuits

Unforced

An unforced series RLC circuit

Consider an un-forced RLC circuit. We want to find Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle V_C} .

First, we can use KVL and KCL

Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle V_R + V_L + V_C = 0}

Next, we can use Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle i = C \frac{dV_C}{dt}} and substitution to get

Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle RC \frac{dV_C}{dt} + L \frac{d}{dt} \frac{C V_C} {dt} V_C = 0}

Changing the order and moving the constants,

Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle LC \frac{d^2 V}{dt^2} + RC \frac{dV_C}{dt} + V_C = 0}

Moving constants away from the first term to get a second-order differential equation,

Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \frac{d^2V_C}{dt^2} + \frac{R}{L} \frac{dV_C}{dt} + \frac{1}{LC} V_C = 0}

Parallel RLC Circuits

Unforced

A parallel unforced RLC circuit