Ohm’s Law

Introduction

Ohm’s law is a fundamental principle in the field of electronics and electrical engineering. Named after the German physicist Georg Simon Ohm, it describes how current, voltage, and resistance interact in an electrical circuit.

Definition and Equation

Ohm’s law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points. It is usually formulated as:

where:

• is the voltage (in volts),
• is the current (in amperes),
• is the resistance (in ohms).

Understanding Ohm’s Law

Ohm’s law implies that if the voltage across a resistor is increased, the current through it increases proportionally, provided the temperature and other physical conditions remain the same. Conversely, if the resistance is increased (with the voltage constant), the current decreases.

Applications

Ohm’s law is foundational in the analysis and design of electrical and electronic circuits. It is used to calculate unknown values in circuits, for example:

• To find the current in a circuit when the voltage and resistance are known.
• To find the voltage in a circuit when the current and resistance are known.
• To find the resistance in a circuit when the voltage and current are known.

Limitations

While Ohm’s law applies to many electrical and electronic components and circuits, it does not apply to all. For example, it does not hold for components such as diodes and transistors, or for materials exhibiting superconductivity, where resistance can drop to zero.

Conclusion

Ohm’s law is an essential tool for understanding and analyzing electrical circuits. It allows us to calculate missing quantities and predict how changes in voltage, current, and resistance will affect a circuit. Despite its limitations, it is fundamental to the study and application of electronics and electrical engineering.

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