NEIEP Mechanics Practice Exam

What term is used to describe an electrical component's resistance to changes in current?

1. Impedance

2. Reactance

3. Inductance

4. Resistance

The correct answer is: Inductance

The term that best describes an electrical component's resistance to changes in current is inductance. When a current flows through an inductor, it creates a magnetic field, which then induces a counter electromotive force (emf) that opposes changes in the current. This property is rooted in Faraday's law of electromagnetic induction, which states that a changing current generates a magnetic field that can induce voltage in the opposite direction. Inductance is particularly relevant in AC (alternating current) circuits where currents are constantly changing. The presence of inductance allows it to resist changes in current flow, making it fundamental in applications such as transformers, chokes, and other electromagnetic devices. Impedance is a broader term that encompasses not just inductance, but also resistance and reactance, dealing with the total opposition to alternating current. Reactance specifically refers to the opposition to change in voltage and is frequency-dependent, incorporating both inductive and capacitive elements. Resistance, on the other hand, refers to the opposition to current flow in direct current (DC) circuits, lacking the dynamic response to changes elemental to inductance.