Can Kirchoff's laws and Ohm's law be used on circuits with diodes?

Click For Summary

Discussion Overview

The discussion revolves around the applicability of Kirchhoff's laws and Ohm's law in analyzing circuits that include diodes alongside constant voltage and current sources. Participants explore the implications of using these laws in the context of nonlinear circuit elements.

Discussion Character

  • Homework-related, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions whether Kirchhoff's voltage and current laws, as well as Ohm's law, can be applied to circuits with diodes, noting an instance of current flowing backwards through a diode.
  • Another participant asserts that Kirchhoff's laws are valid in all circuits, including those with nonlinear elements like diodes, but points out that the principle of superposition does not apply in such cases.
  • The same participant explains that Ohm's law, defined as V=IR, assumes constant resistance, which does not hold for nonlinear elements, suggesting that resistance can still be defined but is not typically relevant.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of Ohm's law to nonlinear elements, with one asserting its limitations while another emphasizes the validity of Kirchhoff's laws in all contexts. The discussion remains unresolved regarding the nuances of applying these laws to circuits with diodes.

Contextual Notes

The discussion highlights the dependence on the definitions of resistance in nonlinear elements and the implications of using superposition in such circuits. There are unresolved assumptions regarding the behavior of diodes in the context of these laws.

SiennaB
Messages
15
Reaction score
0

Homework Statement



Can Kirchhoff's voltage and current laws, and Ohm's law, be used when analysing circuits with constant voltage and current sources, but also diodes?

I'm trying to analyse such a circuit, and I'm finding that current is flowing backwards through one of the diodes.

Homework Equations



Kirchhoff's Voltage Law: sum of voltage drops in a closed loop is zero.
Kirchhoff's Current Law: sum of currents entering a node equals sum of currents leaving a node.
Ohm's Law: V=IR

The Attempt at a Solution


 
Physics news on Phys.org
Kirchhoff's Laws that is the current law(KCL) and the Voltage law(KVL) is indeed valid everywhere, whether the circuit contains diodes, transistors or any other nonlinear element.

The thing which is not valid with the nonlinear elements in circuit is the principal of superposition.

Regarding your question on Ohm's Law, ohm's law is not basically a law. when we say V=IR, means the resistance of the element is constant. For nonlinear elements resistance in not usually important, as V is not linear to I. We still define resistance of nonlinear elements using R-= V/I or R = dV/dI.
 
  • Like
Likes   Reactions: 1 person
Great, thanks for your reply.
 
you are welcome!
 

Similar threads

Replies
15
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 42 ·
2
Replies
42
Views
7K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
1
Views
2K
Replies
1
Views
4K
  • · Replies 10 ·
Replies
10
Views
4K
Replies
8
Views
2K
  • · Replies 15 ·
Replies
15
Views
7K