# Application of the fundamental laws (setup) | Electrical engineering | Khan Academy | Summary and Q&A

84.8K views
May 21, 2016
by
Application of the fundamental laws (setup) | Electrical engineering | Khan Academy

## TL;DR

This video provides an introduction to circuit analysis, explaining Ohm's Law, Kirchhoff's Laws, and sign conventions.

## Install to Summarize YouTube Videos and Get Transcripts

### Q: What are the fundamental laws used in circuit analysis?

The fundamental laws used in circuit analysis are Ohm's Law, Kirchhoff's Current Law, and Kirchhoff's Voltage Law. Ohm's Law relates the current, voltage, and resistance. Kirchhoff's Current Law states that the sum of currents entering a node is equal to zero, and Kirchhoff's Voltage Law states that the sum of voltages in a loop is equal to zero.

### Q: What is the passive sign convention?

The passive sign convention states that if a voltage is labeled with a positive and negative sign, the current flowing into the positive end is considered positive. It is a convention used in circuit analysis to assign signs to the voltage and current values.

### Q: How are nodes and voltages labeled in circuit analysis?

Nodes in a circuit are labeled with letter names, such as A, B, and C. Voltages across resistors or components are labeled with V and a number, indicating the voltage value. The plus and minus signs indicate the polarity of the voltage.

### Q: What are the unknown currents and voltages in the presented circuit?

In the presented circuit, the unknown currents are i1, i2, and Is, flowing through resistors R1, R2, and the current source respectively. The unknown voltages are V1, V2, and the voltage across node B.

## Summary & Key Takeaways

• The video introduces Ohm's Law and Kirchhoff's Laws, which are fundamental in circuit analysis.

• The concept of sign conventions is explained, particularly the passive sign convention.

• A circuit is presented with a voltage source, resistors, and a current source, and the goal is to analyze and determine all the currents and voltages using the Fundamental Laws.