Time domain equation for RC circuit with AC input

  • #1
eyeweyew
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Schoolwork-type thread moved from the techincal forums to the schoolwork forums
TL;DR Summary: How to find Time domain equation for RC circuit with AC input from inverse laplace transform

For a simple RC circuit with AC input such as this: https://www.electronics-tutorials.ws/wp-content/uploads/2013/08/rc12.gif?fit=310,151?fit=310,226. If the AC input is just a simple sinusoidal vI(t)=Vicos(ωt) and the transfer function is Vo/Vi=1/(1+sRC). The inverse Laplace transform of Vo/Vi is e-t/RC/RC. How exactly do I find the Time domain equation for vO(t) from this inverse laplace transform? I cannot seem to find any reference to show how to do that.
 
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  • #2
1705889727687.png
 
  • #3
Have you tried searching the web for this. I looked for "solve RC circuit with Laplace transforms" and got lots of links that looked good.

Is this a home work problem? At what point in the analysis are you getting confused? Can you show us what you've tried so far?
 
  • #4
If ##\frac{V_o(s)}{V_i(s)} = \frac{1}{(1+sRC)}## then ##V_o(s) = \frac{1}{(1+sRC)} V_i(s) ##

## v_o(t) = \mathcal L^{-1}(V_o(s)) = \mathcal L^{-1}(\frac{1}{(1+sRC)} V_i(s)) ##

What is ## V_i(s) ##?
 
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  • #5
I think I got it. Thanks!
 
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Likes DaveE

1. How is the time domain equation derived for an RC circuit with AC input?

The time domain equation for an RC circuit with AC input can be derived by analyzing the behavior of the circuit using Kirchhoff's laws and applying the concept of complex impedance. By considering the voltage across the resistor and capacitor as functions of time, we can determine the differential equation that describes the circuit's response to an AC input signal.

2. What is the general form of the time domain equation for an RC circuit with AC input?

The general form of the time domain equation for an RC circuit with AC input is a first-order linear differential equation of the form: Vout(t) = Vin * (1 - e^(-t/RC)), where Vout(t) is the output voltage across the capacitor, Vin is the input voltage, t is time, R is the resistance of the circuit, and C is the capacitance of the capacitor.

3. How does the time constant affect the response of an RC circuit with AC input?

The time constant, τ = RC, determines how quickly the output voltage of an RC circuit with AC input reaches a steady-state value. A smaller time constant results in a faster response time, while a larger time constant leads to a slower response time. The time constant also affects the frequency response of the circuit, with lower time constants allowing for higher frequencies to pass through the circuit.

4. What is the phase shift in an RC circuit with AC input?

In an RC circuit with AC input, the output voltage lags behind the input voltage by a phase shift angle that depends on the frequency of the input signal. This phase shift is given by φ = arctan(-1/(2πfRC)), where f is the frequency of the input signal. The phase shift is negative for an RC circuit, indicating that the output lags behind the input.

5. How does the amplitude of the input signal affect the output of an RC circuit with AC input?

The amplitude of the input signal in an RC circuit with AC input directly affects the amplitude of the output signal. A larger input signal amplitude results in a larger output signal amplitude, while a smaller input signal leads to a smaller output signal. The relationship between the input and output amplitudes is determined by the impedance of the circuit components and the frequency of the input signal.

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