Kirchhoff's current law and voltage law, defined by Gustav Kirchhoff, describe the relation of values of currents that flow through a junction point and voltages in a an electrical circuit loop, in an electrical circuit.
Kirchhoff’s rules, two statements about multi-loop electric circuits that embody the laws of conservation of electric charge and energy and that are used to determine the value of the electric current in each branch of the circuit.
The first rule, the junction theorem, states that the sum of the currents into a specific junction in the circuit equals the sum of the currents out of the same junction. Electric charge is conserved: it does not suddenly appear or disappear; it does not pile up at one point and thin out at another.
The second rule, the loop equation, states that around each loop in an electric circuit the sum of the emf’s (electromotive forces, or voltages, of energy sources such as batteries and generators) is equal to the sum of the potential drops, or voltages across each of the resistances, in the same loop. All the energy imparted by the energy sources to the charged particles that carry the current is just equivalent to that lost by the charge carriers in useful work and heat dissipation around each loop of the circuit.
Kirchhoff's Current Law (KCL)
This is Kirchhoff's first law.
The sum of all currents that enter an electrical circuit junction is 0. The currents enter the junction have positive sign and the currents that leave the junction have a negative sign:
Another way to look at this law is that the sum of currents that enter a junction is equal to the sum of currents that leave the junction:
I1 and I2 enter the junction
I3 leave the junction
I1=2A, I2=3A, I3=-1A, I4= ?
∑Ik = I1+I2+I3+I4 = 0
I4 = -I1 - I2 - I3 = -2A - 3A - (-1A) = -4A
Since I4 is negative, it leaves the junction.
This is Kirchhoff's second law.
The sum of all voltages or potential differences in an electrical circuit loop is 0.
VS = 12V, VR1 = -4V, VR2 = -3V
VR3 = ?
∑Vk = VS + VR1 + VR2 + VR3= 0
VR3 = -VS - VR1 - VR2 = -12V+4V+3V = -5V
The voltage sign (+/-) is the direction of the potential difference.
Currently, we have around 1977 calculators, conversion tables and usefull online tools and software features for students, teaching and teachers, designers and simply for everyone.
You can find at this page financial calculators, mortgage calculators, calculators for loans, calculators for auto loan and lease calculators, interest calculators, payment calculators, retirement calculators, amortization calculators, investment calculators, inflation calculators, finance calculators, income tax calculators, compound interest calculators, salary calculator, interest rate calculator, sales tax calculator, fitness & health calculators, bmi calculator, calorie calculators, body fat calculator, bmr calculator, ideal weight calculator, pace calculator, pregnancy calculator, pregnancy conception calculator, due date calculator, math calculators, scientific calculator, fraction calculator, percentage calculators, random number generator, triangle calculator, standard deviation calculator, other calculators, age calculator, date calculator, time calculator, hours calculator, gpa calculator, grade calculator, concrete calculator, subnet calculator, password generator conversion calculator and many other tools and for text editing and formating, downloading videos from Facebok (we built one of the most famous Facebook video downloader online tools). We also provide you online downloanders for YouTube, Linkedin, Instagram, Twitter, Snapchat, TikTok and other social media sites (please note we does not host any videos on its servers. All videos that you download are downloaded from Facebook's, YouTube's, Linkedin's, Instagram's, Twitter's, Snapchat's, TikTok's CDNs. We also specialise on keyboard shortcuts, ALT codes for Mac, Windows and Linux and other usefull hints and tools (how to write emoji online etc.)
There are many very usefull online free tools and we would be happy if you share our page to others or send us any suggestions for other tools which will come on your mind. Also in case you find any of our tools that it does not work properly or need a better translation - please let us know. Our tools will make your life easier or simply help you to do your work or duties faster and in more effective way.
These below are the most commonly used by many users all over the world.
- Free online calculators and tools
- Time zones/Clocks/Dates calculators
- Free online units conversion tools
- Free online web design tools
- Free online electricity & electronics tools
- Online Tools
- Text Tools
- PDF Tools
- Basic Electrical Terms
- Electrical & Electronic Units
- Electronic Components
- Electrical & Electronic Symbols
- Electronic Circuit Laws
- Coulomb's law
- DC circuit laws
- How to save electricity
- How to save energy
- Kirchhoff's laws (KVL / KCL)
- Ohm's law
- Voltage divider rule
And we are still developing more. Our goal is to become the one-stop, go-to site for people who need to make quick calculations or who need to find quick answer for basic conversions.
Additionally, we believe the internet should be a source of free information. Therefore, all of our tools and services are completely free, with no registration required. We coded and developed each calculator individually and put each one through strict, comprehensive testing. However, please inform us if you notice even the slightest error – your input is extremely valuable to us. While most calculators on Justfreetools.com are designed to be universally applicable for worldwide usage, some are for specific countries only.