What is one ohm defined as?

One ohm is defined as the resistance that allows one ampere of current to flow when one volt is applied across it. This relationship is expressed by Ohm's Law, which states that voltage (V) is equal to the current (I) multiplied by the resistance (R), or V = I × R.

In this case, applying one volt across a conductor that has a resistance of one ohm will produce a current of one ampere. This direct ratio between voltage, current, and resistance is foundational in electrical engineering and confirms the precise definition of one ohm.

The other options present variations of this relationship but either involve different current or voltage values that distort the core definition of an ohm. Thus, option B accurately captures the fundamental aspect of electrical resistance defined in ohms.