# The capacitance value that makes the voltage in phase with current

What's the value of the capacitor that makes the voltage in phase with current , and then what's the circuit current and power?

• Looks like homework without any effort on your part. Add details of what you tried and where you are stuck. Dec 5, 2017 at 22:39
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• You will learn to match reactive impedances at resonance. Dec 5, 2017 at 22:53

## 2 Answers

To find the Xc that makes the voltage in phase with the current, you have to find the equivalent impedance of that branch. Then, you can find the current through Ohm's first law. So you have to think a little with these results. If you use phasor diagram may help you to understand this phenom.

Well, the input impedance is given by:

$$\underline{\text{Z}}_{\space\text{in}}=6,25+1,25\text{j}+\frac{1}{\frac{1}{5}+\frac{1}{5+\frac{1}{100\pi\text{C}\text{j}}}}\tag1$$

Let's say that the input voltage is a sine wave without any phase difference, so we need that:

$$\arg\left(\underline{\text{Z}}_{\space\text{in}}\right)=0\space\Longleftrightarrow\space\text{C}=\frac{1}{1000\pi}\tag2$$