In the context of Ohm's law, what SI unit is used to measure electrical resistance?

• A. Watt ($W$)
• B. Ohm ($\Omega$)
• C. Volt ($V$)
• D. Ampere ($A$)

Answer: (B)

Verified step by step guidance

1. Recall that Ohm's law relates voltage (V), current (I), and resistance (R) through the formula \(V = I \times R\).
2. Understand that voltage (V) is measured in volts (V), current (I) is measured in amperes (A), and resistance (R) is measured in ohms (\Omega).
3. Recognize that the unit of resistance, the ohm (\Omega), is defined as the resistance between two points of a conductor when a constant potential difference of one volt applied between these points produces a current of one ampere.
4. Note that the watt (W) is a unit of power, not resistance, and the ampere (A) is a unit of current, while the volt (V) is a unit of electric potential difference.
5. Therefore, the SI unit used to measure electrical resistance in the context of Ohm's law is the ohm (\Omega).