A fundamental principle of electrical circuits stating that current is directly proportional to voltage and inversely proportional to resistance.

Ohm's Law

Ohm's Law, discovered by German physicist Georg Ohm in 1827, represents one of the most fundamental relationships in electrical circuits. It is expressed by the equation:

V = IR

Where:

V represents voltage (measured in volts)
I represents current (measured in amperes)
R represents resistance (measured in ohms)

Physical Significance

At its core, Ohm's Law describes how electrical resistance impedes the flow of electric current through a conductor. This relationship is analogous to how friction affects water flowing through a pipe:

Higher voltage (like higher pressure) increases current flow
Higher resistance (like a narrower pipe) decreases current flow

Applications

Circuit Analysis

Basic circuit design
Power calculation (P = VI)
voltage drop calculations
current division in parallel circuits

Practical Uses

Electronics troubleshooting
Component selection
Power supply design
Battery life calculations

Limitations

Ohm's Law assumes:

Linear behavior of components
Constant temperature
DC or steady-state AC conditions

Some components, known as non-ohmic devices, do not follow this law:

Historical Impact

The discovery of Ohm's Law marked a pivotal moment in the development of electrical engineering. It provided the first quantitative description of electrical circuit behavior, laying groundwork for:

Mathematical Variations

The law can be expressed in three equivalent forms:

V = IR (voltage form)
I = V/R (current form)
R = V/I (resistance form)

These variations make it versatile for solving different types of circuit problems.

Teaching and Learning

Ohm's Law is often introduced through the "Ohm's Law Triangle," a mnemonic device that helps students remember the relationships between:

This foundational concept serves as a gateway to more advanced topics in electrical theory and circuit analysis.