What is the basic unit of inductance?

• A. The Farad
• B. The Ohm
• C. The Henry
• D. The Volt

Answer: (C)

Inductance is the property that relates how much voltage is induced when current changes in a circuit. The fundamental relation is V = L · (dI/dt). The unit that expresses inductance is volt-second per ampere, which we call the Henry. So one Henry means that if the current through an inductor changes at a rate of one ampere per second, the induced voltage is one volt. In practice, inductors are often measured in smaller units like millihenries or microhenries. The Henry is named after Joseph Henry, a pioneer in electromagnetic discovery. The other units—Farad, Ohm, and Volt—correspond to capacitance, resistance, and potential difference, respectively, not inductance.