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

• A. ohm ($\Omega$)
• B. watt ($W$)
• C. volt ($V$)
• D. ampere ($A$)

Answer: (A)

Verified step by step guidance

1. Understand that electrical resistance is a measure of how much a material opposes the flow of electric current.
2. Recall Ohm's law, which relates voltage (V), current (I), and resistance (R) through the formula \(R = \frac{V}{I}\).
3. Identify the SI units for voltage and current: voltage is measured in volts (V) and current in amperes (A).
4. Using the formula \(R = \frac{V}{I}\), the unit of resistance is derived as volts per ampere, which is defined as the ohm, symbolized by \(\Omega\).
5. Therefore, the SI unit used to measure electrical resistance is the ohm (\(\Omega\)).