What is the practical unit used to measure resistance?

The practical unit used to measure resistance is the Ohm. Resistance is a property of a material that determines how much it resists the flow of electric current. It is directly defined in terms of voltage and current with Ohm’s Law, which 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. This relationship can be expressed using the formula V = I × R, where V is voltage, I is current, and R is resistance measured in Ohms.

The Ohm is a derived unit in the International System of Units (SI), named after the German physicist Georg Simon Ohm, who formulated the foundational law related to electricity. Understanding resistance and the Ohm is crucial for engineers, as it helps in designing circuits and understanding how materials will behave under electrical loads.