Hamburger Menu

Ohms explained

The ohm is the standard unit of electrical resistance in the International System of Units (SI). Represented by the Greek letter omega, the ohm measures how much a material opposes the flow of electric current. One ohm is defined as the resistance between two points of a conductor when a constant potential difference of one volt produces a current of one ampere.

Symbol

The symbol for the ohm is Ω. This uppercase Greek letter omega is universally recognized in scientific and engineering contexts to denote electrical resistance.

Applications and Uses

The ohm is used to specify the resistance of components like resistors, wires, and electronic devices. It helps engineers design safe, efficient, and functional circuits for everything from household appliances to advanced computing systems.

  • Used to rate resistors and other electrical components
  • Essential for calculating voltage, current, and power in circuits
  • Critical for troubleshooting and repairing electrical systems
  • Applied in both direct current (DC) and alternating current (AC) circuits

Measurement Tools

Ohms are measured using instruments such as ohmmeters, multimeters, and bridge circuits. These tools provide accurate resistance readings, which are vital for circuit analysis, quality control, and maintenance.

Origin

The ohm is named after Georg Simon Ohm, a German physicist and mathematician who formulated Ohm’s Law in the 19th century. His pioneering work established the fundamental relationship between voltage, current, and resistance, laying the groundwork for modern electrical science.

FAQs

How is the ohm defined in terms of SI base units?

The ohm is defined in SI base units as kg·m²·s⁻³·A⁻², combining the kilogram, meter, second, and ampere to express electrical resistance.

Can resistance values be negative or zero in ohms?

In practical terms, resistance in ohms is always zero or positive. Zero ohms indicates a perfect conductor, while negative resistance is a rare phenomenon found only in specialized electronic components.

What is the relationship between ohms, volts, and amperes?

According to Ohm’s Law, resistance (ohms) equals voltage (volts) divided by current (amperes): R = V/I. This relationship is foundational in electrical engineering.