Explanation: Inductance is a fundamental property of an electrical conductor, especially a coil, that opposes changes in current flowing through it. When current passes through an inductor, it creates a magnetic field. If the current changes, the magnetic field also changes, inducing a voltage across the inductor that opposes the original change in current. This property is measured in **Henrys (H)**, named after American physicist Joseph Henry, who discovered electromagnetic induction independently of Michael Faraday. In amateur radio, inductors are vital components used in resonant circuits, filters, and chokes to store energy in a magnetic field and manipulate AC signals. The other options are incorrect: * **Joule** is the unit of energy. * **Coulomb** is the unit of electric charge. * **Ohm** is the unit of electrical resistance.