Basic concepts, Electronics, Energy, Projects, Robotics, Telecomunications

Resistance, Capacitance, Inductance, Impedance and Reactance

This is another post about basic concepts of electricity. This time I will talk about resistors, capacitors, inductors in CC and AC.

Click here to see introduction to electromagnetism.

Introduction to electromagnetism Introduction to electromagnetismClick here

Resistance

Resistance is a value that measures how much the component “resist” the passage of electrical current, the value is measured in ohms (Ω). One way to calculate resistance:

R=\rho \frac{L}{A}

  • \rho is the resistivity, a material’s property.

Another form to calculate the resistance is applying Ohm’s law.

R=\frac{V}{I}

  • V is the voltage and I is the current.

This is the resistor, the component with a defined resistance and the resistor’s color code.

Resistors in series, the resistance is summed.

R_{total}=R1+R2

Resistors in parallel:

\frac{1}{R_{total}}=\frac{1}{R1}+\frac{1}{R2}

In AC circuits with very high frequency, the resistance even in resistors varies, passive components in high frequency stays to another post.

Capacitance

Capacitance is the capacity to store energy in a capacitor, is measured in farads (F), these are capacitors.

Capacitance is calculated in this form:

C=\frac{Q}{V}

  • Q is the charge and V is the voltage.

The capacitance in a capacitor with parallel plates.

C=\epsilon \frac{A}{d}

  • \epsilon is the electric permissiveness;
  • A is the plate area;
  • d is the distance between plates.

Capacitance in a cylindrical capacitor.

C=2\pi \epsilon \frac{L}{ln(\frac{b}{a})}

  • L is the cylinder’s length.

Capacitance in a spherical capacitor.

  C=4\pi \epsilon \frac{ab}{b-a}

Capacitance in a isolated sphere.

C=4\pi \epsilon R

Capacitors in series:

\frac{1}{C_{total}}=\frac{1}{C_{1}}+\frac{1}{C_{2}}

Capacitors in parallel:

C_{total}=C_{1}+C_{2}

Inductance

While the capacitor stores energy in an electrical field, the inductor stores energy in a magnetic field. Inductance is the inductor’s capacity to resist variation of electric current and is measured in henries (H). The inductor is nothing more than a rolled wire in spirals which can have a nucleus inside to increase the magnetic field and the inductance. Here are various types of inductors. Sometimes inductors are called solenoids.

The formula to calculate inductance in a solenoid:

L=\frac{\mu N^{2}A}{l}

  • \mu is the magnetic permeability;
  • N is the number of spires or turns in the inductor;
  • A is the section area;
  • l is the length.

The equation to calculate the inductance of a toroid, ring-shaped coil. With a square cross section.

L=\frac{\mu N^{2}h}{2\pi }ln\frac{b}{a}

If the cross section area is circular.

The inductor’s association in series and parallel is equal to the resistors and the total inductance is calculated in the same way.

Impedance and Reactance

In the alternated current, the value of resistance in the passive components (resistor, capacitor, and inductor) is called impedance, which is formed by reactances. In the resistor, the impedance is equal to the resistance value in the CC. In capacitors and inductors, the reactance is an imaginary number and are called respectively capacitive reactance and inductive reactance.

Capacitive reactance.

X_{c}=\frac{1}{\omega C}

  • C is the capacitance and \omega is the circuit’s frequency in radians/s.

Inductive reactance.

X_{l}=\omega L

This graphic shows the impedance as Z, reactances as X_{c} and X_{l} in the imaginary axis and the resistance in the real numbers axis.

Impedances of capacitor and inductor are respectively.

Z_{c}=-j\frac{1}{\omega C}=\frac{1}{j\omega C}

Z_{l}=j\omega L

Edition: More information about capacitance and inductance in the link below.

Capacitance and inductance: More informationClick here

Liked it? Take a second to support Electrical e-Library on Patreon!

About Pedro Ney Stroski

36 thoughts on “Resistance, Capacitance, Inductance, Impedance and Reactance

  1. I simply want to say I am newbie to weblog and seriously loved you’re page. Most likely I’m planning to bookmark your site . You amazingly have terrific stories. Thanks a lot for sharing with us your web-site.

  2. F*ckin’ amazing things here. I’m very glad to peer your post. Thanks so much and i am looking forward to contact you. Will you please drop me a e-mail?

  3. What i don’t realize is if truth be told how you are not actually a lot more neatly-liked than you may be right now. You’re so intelligent. You know thus considerably with regards to this matter, made me personally imagine it from numerous varied angles. Its like men and women are not involved until it is one thing to accomplish with Woman gaga! Your individual stuffs excellent. Always care for it up!

  4. certainly like your web site however you have to check the spelling on several of your posts. A number of them are rife with spelling problems and I to find it very bothersome to tell the truth on the other hand I¡¦ll surely come back again.

  5. A lot of thanks for your whole efforts on this website. Kate take interest in making time for internet research and it’s obvious why. My spouse and i notice all relating to the lively method you convey informative guidance via this web blog and cause contribution from other individuals on this article while our favorite simple princess is without a doubt being taught a lot. Enjoy the remaining portion of the year. You’re the one doing a powerful job.

  6. Thanks for the sensible critique. Me and my neighbor were just preparing to do some research on this. We got a grab a book from our local library but I think I learned more clear from this post. I am very glad to see such wonderful information being shared freely out there.

  7. excellent put up, very informative. I ponder why the other experts of this sector do not notice this. You must continue your writing. I am confident, you’ve a great readers’ base already!

  8. What i do not understood is if truth be told how you’re now not actually a lot more well-liked than you may be right now. You’re very intelligent. You realize therefore significantly in relation to this subject, made me for my part consider it from a lot of numerous angles. Its like women and men don’t seem to be involved unless it is one thing to do with Girl gaga! Your personal stuffs outstanding. Always care for it up!

  9. of course like your web site but you need to check the spelling on several of your posts. Several of them are rife with spelling issues and I find it very troublesome to inform the truth then again I will surely come back again.

  10. Thanks for one’s marvelous posting! I truly
    enjoyed reading it, you may be a great author. I will ensure that I bookmark your blog and will
    often come back someday. I want to encourage you to continue your great job,
    have a nice day!

  11. I savour, result in I found just what I used to be taking a look for. You’ve ended my 4 day long hunt! God Bless you man. Have a great day. Bye|

Leave a Reply

Your email address will not be published. Required fields are marked *