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◉ Science·2 min·Updated Mar 11, 2026

What is Ohm's Law?

Ohm's Law

Quick Answer

This law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance of the conductor. It is commonly expressed with the formula V = IR, where V is voltage, I is current, and R is resistance.

Overview

Ohm's Law is a fundamental principle in physics that describes the relationship between voltage, current, and resistance in an electrical circuit. It indicates that if you increase the voltage across a conductor, more current will flow, provided the resistance remains constant. Conversely, if the resistance increases, the current will decrease for a given voltage. This relationship is essential for understanding how electrical devices operate and are designed. In practical terms, consider a simple circuit with a battery and a light bulb. If the battery provides a higher voltage, the bulb will shine brighter because more current flows through it. However, if you add a resistor to the circuit, the resistance increases, and the bulb will dim because less current can flow. This demonstrates how Ohm's Law helps engineers and electricians design circuits that function safely and efficiently. Ohm's Law matters because it allows us to predict how electrical components will behave under different conditions. It is used in various applications, from household wiring to complex electronic devices. By understanding this law, people can troubleshoot electrical issues and ensure that devices operate within safe limits.

Frequently Asked Questions

The formula for Ohm's Law is V = IR, where V represents voltage, I represents current, and R represents resistance. This equation helps to calculate any one of the three variables if the other two are known.
Ohm's Law is applied in everyday electrical systems, such as household wiring and electronic devices. For example, it is used to determine the appropriate resistor needed in a circuit to ensure that a light bulb operates at the correct brightness.
Ohm's Law applies primarily to ohmic materials, which have a constant resistance regardless of the voltage and current. However, some materials, like semiconductors and superconductors, do not follow Ohm's Law under certain conditions.