SI unit for electrical resistance In basic electrical measurements, what is the standard unit (designator) used to express the value of resistance?

Introduction / Context:
Every electrical quantity has an SI unit. Recognizing the correct unit for resistance is essential for interpreting datasheets, calculating with Ohm’s law, and selecting components. The unit symbol and name are universally standardized to avoid confusion in engineering practice.

Given Data / Assumptions:

• Quantity: electrical resistance.
• We are working with SI units and standard circuit theory.
• Symbols: A for ampere, V for volt, W for watt, Ω (ohm) for resistance.

Concept / Approach:
By definition, resistance R relates voltage and current via Ohm’s law: V = I * R. The SI unit for R is the ohm (Ω), which is equivalent to volt per ampere (V/A). Knowing this allows dimensional checks in formulas and helps avoid unit mistakes.

Step-by-Step Solution:
Recall Ohm’s law: V = I * R.Rearrange to R = V / I.Units: V/A is defined as one ohm (Ω).Therefore, the correct unit designator is the ohm.

Verification / Alternative check:
Cross-verify with component labels: resistors are specified in Ω, kΩ, and MΩ. Meters display resistance in Ω as well.

Why Other Options Are Wrong:
Ampere: unit of current.Volt: unit of electric potential.Watt: unit of power.

Common Pitfalls:
Confusing resistance (Ω) with reactance (also expressed in ohms but frequency dependent) or with conductance (siemens, S, the reciprocal of ohms).

Final Answer:
ohm