# Voltage current relationship capacitor conversion

### Capacitor Impedance Calculator - Electrical Engineering & Electronics Tools

In this article, we explain how to convert an AC circuit from the time domain to the Capacitor impedance formula for converting capacitance from the time to the component that symbolizes this relationship between voltage and current. Reactance (X) conveys a component's resistance to alternating current. phase shift between voltage and current that occurs in a purely capacitive circuit. To convert this to the impedance of a capacitor, simply use the formula Z = -jX. The inverse relationship between reactance and frequency explains why we use. If there is a current going into the capacitor, the value of the charge on the plates will change. .. This will change the voltage loop equation.

A current source becomes a force generator, and a voltage source becomes an input velocity. This is best illustrated with an example. Procedure for Conversion from Electrical to Mechanical 1 The conversion from an electrical circuit to a mechanical 1 analog is easily accomplished if capacitors in the circuit are grounded.

### AC Circuit Analysis- Time to Frequency Domain Conversion

If they are not, the process results in a mechanical system where positions must be chosen very carefullyand the process can be much more difficult. Label all node voltages. Write a node equations for each node voltage Re-write the equations using analogs make making substitutions from the table of analogous quantitieswith each electrical node being replaced by a position. Draw the mechanical system that corresponds with the equations.

Another way to do the switch from electrical to mechanical 1, is by simply redrawing the electrical circuit using mechanical components.

Each node becomes a position or velocity Label currents, positions, and mechanical elements as they were in the original electrical circuits.

This diagram is that same diagram as that obtained previouslyso we know it is correct. This circuit was drawn with the capacitor grounded. We need this value to compute the reactance of the capacitor in the frequency domain.

Doing this we get, Z L The j value, again, represents the phase of the component. Capacitors, in the frequency domain, will always have a negative j value.

## AC Capacitor Circuits

A negative j value symbolizes that the voltage lags the current. Current goes through a capacitor before volage is formed across the capacitor. A negative j value is just an imaginary component that symbolizes this relationship between voltage and current.

So this is how capacitors can be converted to the frequency domain from the time domain. Inductors The next component we will focus on is the inductor. An inductor, just like a capacitor, is a reactive component.

## AC Circuit Analysis- Time Domain to Frequency Domain Conversion

The formula to convert the inductance from the time to the frequency domain is shown below. So the formula to convert an inductance value from the time to the frequency domain is shown above. We need this again to compute the reactance of the inductor in the frequency domain.

So going back to the inductance formula, we take it and plug in the inductor value, mH, into the formula. Inductors, in the frequency domain, will always have a positive j value. A positive j value symbolizes that the voltage leads the current. Voltage is built up across an inductor before current is allowed through. A positive j value is just an imaginary component that symbolizes this relationship between voltage and current.

So this is how inductors can be converted to the frequency domain from the time domain. Power Source The last component to convert to the frequency domain is the power source itself. This is made obvious by the t in the formula.

However, this, too, must be changed to the frequency domain and how it is representated in the frequency domain is in phasor format.

Phasor form simply represents the amplitude of the signal and the phase. It doesn't take into account frequency because we've already computed the frequency into each of the components already.

Therefore, it doesn't need to be emphasized again. We're going to go through one more circuit and do a full analysis on it as could be done with a DC signal.

AC Circuit Time to Frequency Domain- Full Example So the circuit we're going to full convert from the time domain to the frequency domain and analyze fully is shown below. So the first thing is to individually convert all the values to the frequency domain. The power source, 15 cos 50t is represented in phase form by 15 All the resistors keep their same value.

This circuit is now shown below in the frequency domain. Now that the circuit is fully converted, we can analyze the circuit using common circuit analysis techniques, such as KCL or KVL. This particular circuit lends well to KCL analysis, so that is how we will analyze it. At that node, current flows from the node into the capacitor and from the node into the mH inductor.

So you just have to be consistent with your positive and negative symbols. We'll adopt the convention of current entering a node being positive and current leaving a node being negative.

- Analogous Electrical and Mechanical Systems
- Capacitor Impedance Calculator

So taking this into account, we get this mathematic result shown below.