# Solving non-series (L)RC problems?

• jehan60188
In summary, solving for voltage, current, impedance, and other parameters in circuits involves applying Kirchhoff's laws, using differential equations, and possibly using Laplace transforms for simpler solutions. For circuits with only one type of reactive component, the rules of thumb for t=0, t=0+, and t→∞ can be used to set boundaries for operation. It is also helpful to practice problems to gain a better understanding of how capacitors and inductors behave in DC circuits.
jehan60188

## Homework Statement

given circuits such as

http://img196.imageshack.us/img196/8599/48692547.gif

or

http://img854.imageshack.us/img854/1848/50833427.gif

how does one solve for voltage, current, impedance, etc?
is it a matter of kirchhoffs loop + junction rules, and differential equations?

like, what's the charge on the capacitor at time t?
or potential energy in the circuit?
or other stuff, i guess

## Homework Equations

v=IR
Z = sqrt(R-(XL-XC)^2)
only for a series loop though.

## The Attempt at a Solution

no idea

Last edited by a moderator:
jehan60188 said:
how does one solve for voltage, current, impedance, etc?
is it a matter of kirchhoffs loop + junction rules, and differential equations?

like, what's the charge on the capacitor at time t?
or potential energy in the circuit?
or other stuff, i guess
Yes, all the usual laws apply including KVL, KCL, etc., in order to write differential equations for the circuit which can be solved to yield what you want to find. There are some fancy techniques that you'll eventually come across (such as Laplace transforms) which will make your life much easier in the regard

When a circuit contains just one type of reactive component, L or C, then often the formal writing and solving of differential equations for the circuit can be dispensed with because the form of the solution will invariably be that of an exponential charge or discharge, and the rules of thumb for t=0, t=0+, t→∞ for L and C in DC circuits can set the boundaries of operation.

## Homework Equations

v=IR
Z = sqrt(R-(XL-XC)^2)
only for a series loop though.

## The Attempt at a Solution

no idea
Since you've got DC voltage sources you're looking for the transient response of the LC circuit, so XL and XC aren't going to do you too much good here.

You can write either loop equations or node equations that use the calculus "definitions" for the L and C components, thus resulting in the differential equations for the circuit.

doing practice problems was super helpful- I realized that a capacitor acts like an open wire at t=0, and an inductor acts like an open wire at t = infinity (for a DC circuit). very helpful for modelling!

## 1. What is a non-series (L)RC circuit?

A non-series (L)RC circuit is an electrical circuit that contains at least one element that is not connected in series with other elements. This can include elements such as capacitors, inductors, or resistors.

## 2. How do you solve non-series (L)RC problems?

To solve non-series (L)RC problems, you must first analyze the circuit to determine the values of the elements involved. This can be done through calculations or by using circuit analysis techniques such as Kirchhoff's laws. Once the values are known, you can apply the appropriate equations to find the desired solution.

## 3. What are some common challenges when solving non-series (L)RC problems?

Some common challenges when solving non-series (L)RC problems include dealing with non-linear elements, such as diodes or transistors, and understanding the interactions between the different elements in the circuit. In addition, keeping track of the different equations and techniques can also be a challenge.

## 4. Is there a general method for solving non-series (L)RC problems?

While there is no one-size-fits-all method for solving non-series (L)RC problems, there are some general steps that can be followed. These include analyzing the circuit, determining the values of the elements, applying the appropriate equations, and checking the solution for accuracy.

## 5. Can software or calculators be used to solve non-series (L)RC problems?

Yes, software and calculators can be useful in solving non-series (L)RC problems. There are many circuit analysis programs available that can handle complex circuits with ease. However, it is important to understand the underlying principles and equations in order to use these tools effectively.

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