# What is Kirchhoff law: Definition and 24 Discussions

Gustav Robert Kirchhoff (German: [ˈkɪʁçhɔf]; 12 March 1824 – 17 October 1887) was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects.He coined the term black-body radiation in 1862. Several different sets of concepts are named "Kirchhoff's laws" after him, concerning such diverse subjects as black-body radiation and spectroscopy, electrical circuits, and thermochemistry. The Bunsen–Kirchhoff Award for spectroscopy is named after him and his colleague, Robert Bunsen.

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1. ### Sign conventions for Kirchhoff's loop rule

Battery and Capacitor For a battery (or capacitor), the potential increases by ##\mathcal{E}## (or ##\displaystyle\frac{q}{C}##) as we move from -ve to +ve terminal (or plate) regardless of the direction of the assumed current. Resistor and Inductor Suppose we are traversing the loop in the...
2. ### Application Of Kirchoff Law (Desert)

Homework Statement:: Sand is rough and black so it is a good absorber and radiator of heat depending on temperature. During the day, sand's radiation of the sun's energy superheats the air and causes temperatures to soar. But, at night most of the heat in the sand quickly radiates into the air...
3. ### Using Kirchhoff's Rule - Theory question

In my lecture, it was explained that Kirchhoff's Rule is used when circuits are too "complicated" to simplify by combining resistances in series and parallel. I do not understand in which cases I can simplify circuits by combining resistances, and on which cases I can only use Kirchoff's Rule...
4. ### How to use Kirchhoff's voltage law on this circuit?

In this circuit, I have to find the potential at point O. I tried using Kirchhoff's voltage law for the three open loops AOC, AOB and BOC to arrive at potential at O. According to my calculations the potential at O should be 0, but that is not the case according to the source. So I must be using...
5. ### Engineering Kirchoff's Law Problem about this Induction Generator circuit

Hi, Please find attached below the Induction Generator circuit. I have the following parameters: Parameter Value Rs = Rr (Resistance on stator and rotor) 0.2 Ω Ls = Lr (inductance on stator and rotor) 5 mH = 0.005 H p (number of pairs of poles) 2 f (frequency) 60 Hz Vsl (stator line...
6. ### Find the supply voltage of a ladder circuit

Find the supply voltage of a ladder circuit shown, so that I=7A. Assume R=11Ω. (The unit must be placed) Hello, everyone. Please, help me with this. Could someone explain to me how to solve such tasks. I literally spent the whole day watching Khan Academy and trying to figure out how to solve...
7. ### Two batteries and two resistors circuit - wrong possible answers ?

It's ABCD question with answers attached. Problem is that, I don't think that neither of those are correct. From KVL the equation seems to be i = (E2-E1)/(2r1+2r2 + R). I've attached images of the circuit, answers, and my solution. Can someone please point me if I am wrong, and if yes, where's...
8. ### Kirchoff's laws and capacitance

Equivalent capacitance before and after remains the same. Now the 10F capacitor (which was initially connected in parallel with 20F) would have 30 C charge. Hence an additional 20C must have been supplied to it. The only path which may supply the charge is through battery. However this leads...
9. ### Calculate the voltage in a circuit

Homework Statement Given the following circuit, find the values of V1 and V2. Homework Equations The second law of Kirchhoff states that the sum of all voltajes must equal 0 The Attempt at a Solution I found in the book that the solution is V1: 15V and V2: 14V I tried to solve V1 by adding 9...
10. ### How would I solve this Mixed Circuit?

Homework Statement The following circuit is given, and all voltage, current, resistance and power must be found for each resistor. I have found the following information: Vsrc = ? Isrc = .5A Rsrc = ? Psrc = ? V1 = ? I1 = .5A R1 = ? P1 = ? V2 = 2.5V I2 = .25A R2 = 10 P2 = .625W V3 =...
11. ### Engineering Computing resistance in given circuit with BJT

Hi, before you proceed with reading this question, I would like you to know what I do not expect anyone to solve this task for me. I have a problem with a single step in the solution and I'm only asking you to help me with this one step. 1. Homework Statement Compute ##R_B## so that Q-point of...
12. ### A Explain the demonstration of Kirchhoff's law on blackbody

The Kirchhoff law of dependence of energy emitted from a blackbody only on wave length and temperature was demonstrated by Kirchhoff in a paper in the year 1859. The paper is in german naturally but I found it translated in english in a book of prof. Brace in 1901. A lot of time ago. But my...
13. ### Using Kirchhof's laws to solve a circuit

Homework Statement In the circuit shown in the figure (attached with the solution). Determine: 1. the reading of the ammeter when the key (K) is open. 2. The reading of the ammeter when the key (K) is closed. Homework EquationsThe Attempt at a Solution [/B] What confuses me in the circuit...
14. ### A Physical Understanding of Kirchhoff's Laws

< Mentor Note -- thread moved to the EE forum from the Homework forums since it is a more general set of questions > So, we are going into Kirchhoff's Laws in class, and my entire understanding of circuits, which took me a while to form, is again falling apart. A physical understanding is...
15. ### Is my solution for Kirchoff's Rules Problem correct?

Homework Statement Homework Equations V = IR P = IV The Attempt at a Solution The attempt is much too long to type out, so here is a link to a picture of my work. I'm mostly concerned about part C, because I've seen some similar problems and my answer has been different by a magnitude of 10...
16. ### Find the current and Voltage of the following pieces

Homework Statement Above is the circuit I have to deal with. We are given the Vin = 6V, Vout = 3.367 V and all the R values. We are asked to find the remaining values (The I's and V's) Homework Equations [/B] Kirchhoff Voltage and current laws V = IR R's in series add Voltage from a source...
17. ### How to find a current is this specific circuit

Homework Statement Find the voltage Vo for this circuit. Given: is = 36 A Link to circuit: https://session.masteringengineering.com/problemAsset/1824621/4/pr_2-32.jpg Homework Equations V = IR Kirchhoff's laws for current and voltage.The Attempt at a Solution I first noticed that the...
18. ### Finding Voltage Using Junction & Loop Rules

Homework Statement find the voltage between a and d and terminal of each batteries Homework Equations Junction Rule and Loop Rule The Attempt at a Solution I got three equation JR : I3 = I1+I2 LR : 45-I3-47I3-34I1 = 0 45-I3-47I3+85-I2-18I2 = 0 I can't solve these...
19. ### Use Kirchoff's laws to solve for tension and current

Homework Statement http://postimg.org/image/ys43ylstp/ [/B] I need to find tension and current in each element of the circuit. I have included an image of what I have drawn so far for the circuit. http://postimg.org/image/ys43ylstp/ Homework Equations Kirchoff's laws. The Attempt at a Solution...
20. ### A Kirchhoff law for absorption and emission of a gas

Hi Guys I´m studying the absorption and emission phenomena of a gas and, according to Kirchhoff "extended" law, for a body at thermodynamic equilibrium, the following statement is true. ελ(T,θ,φ) = Aλ(T, θ,φ). So, if i understood correctly the meaning of this equation, The amount of absorbed...
21. ### Ground circuit and kirchhoff law(holiday 27.30)

Homework Statement I attatched my question as a picture Homework EquationsThe Attempt at a Solution 1.i found a solution using kirchhoff law, V1=-11V,V2=-9V and it was correct. but i`m not sure that my method was right. i know that kirchhoff law is originated from charge and energy...
22. ### Kirchhoff Law Problem: Find Current and Potential Difference | Solution Included

Homework Statement https://fbcdn-photos-c-a.akamaihd.net/hphotos-ak-xft1/v/t1.0-0/s480x480/12802893_10205707400875867_4855727067132215897_n.jpg?oh=b486598e6f2016a814eb52bf48870334&oe=57648CD9&__gda__=1464637082_3cae40328f43f09eaa2cf9cf5b2f0b0f Homework Equations Kirchhoff Law 1. Find the...
23. ### Finding the magnitude and direction of current thro Kirchhoff law

Homework Statement Revered Members, Please go through my attachment. I have been asked to find the magnitude and direction of current through the 10 ohm resistor. The answer that is given in the book is 1/23 Ampere from A to B. But i solved as given in the attachment but i got the answer...
24. ### Understanding Kirchhoff's Laws: Solving a Parallel Circuit Problem

Homework Statement my work I know part A is incorrect because for my part B my quadratic contains an imaginary,which I doubt he would due. Some help would be awesome since it is due tomorrow, and will probably be on the exam as well.