Definition

1. Noun:
   • Electrical resistance: The property of a material that impedes or opposes the flow of electric current. It is the constant of proportionality in Ohm's law, relating voltage to current.
   • Measurable opposition: This specific opposition is measured in the unit of ohms (Ω) and is often simply called "resistance."

Usage

• General Use: The term is used in physics and electrical engineering to describe a fundamental property of conductors and components.
• Key Concept: It is central to Ohm's law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points, with the ohmic resistance being the constant ratio (R = V/I).

Examples

• In a Sentence:
  • The ohmic resistance of the wire increases with its length and decreases with its cross-sectional area.
  • To calculate the current, you need to know the applied voltage and the total ohmic resistance of the circuit.
  • A resistor is a component specifically designed to provide a precise amount of ohmic resistance in a circuit.

Advanced Usage

• "Pure" or "Ideal" Ohmic Resistance: Refers to a resistance that obeys Ohm's law perfectly across a wide range of voltages and currents, meaning its value is constant. Real-world components like resistors are designed to approximate this ideal.
• Distinction from Impedance: Ohmic resistance is specifically the real, dissipative opposition to current in a direct current (DC) circuit or the resistive component in an alternating current (AC) circuit. It contrasts with "reactance" (opposition due to capacitance or inductance); together, resistance and reactance form "impedance."

Variants and Related Words

• Resistance (R): The most common synonym and abbreviated form.
• Electrical Resistance: A fuller, synonymous term.
• Ohmic: (Adjective) Describing a component or material that exhibits ohmic resistance (e.g., an ohmic conductor).
• Resistor: (Noun) A passive electrical component that implements ohmic resistance.

Synonyms

• Electrical Resistance
• Resistance (R)
• DC Resistance (when specifically distinguishing from AC impedance)

Related Phrases / Compound Terms

• Ohm's Law: The fundamental law (V = I × R) that defines the relationship between voltage (V), current (I), and ohmic resistance (R).
• Non-ohmic Behavior: Describes components (like diodes) where the resistance is not constant and does not obey Ohm's law.

Noun

1. a material's opposition to the flow of electric current; measured in ohms