What is the practical unit of electric-current strength?

The practical unit of electric current strength is the Ampere. The Ampere is defined as the flow of electric charge through a conductor when one coulomb of charge passes through a cross-section of the conductor in one second. This unit is fundamental in electrical engineering and physics, as it allows for the quantification of current, which is crucial for understanding how electrical circuits operate.

In practical terms, when you measure current with an ammeter, the value you read is expressed in Amperes. This measurement is essential for determining how much electricity is flowing in a circuit, which impacts the design and functioning of electrical systems.

Other options represent different electrical concepts: the Ohm is the unit of resistance, the Coulomb is the unit of electric charge, and the Volt is the unit of electric potential or voltage. Each of these units plays a significant role in electrical theory, but none directly measure electric current in the way that the Ampere does.