An inductor that opposes any change in current flow is called a(n) what?

• A. Coil
• B. Resistor
• C. Diode
• D. Capacitor

Answer: (A)

An inductor resists changes in current because it stores energy in a magnetic field and generates a voltage that opposes any change in current. The defining relation is v = L di/dt, which means the faster the current tries to change, the stronger the opposing voltage the inductor produces. When current is steady, the opposition isn’t as noticeable, but the moment it tries to rise or fall quickly, the inductor pushes back to smooth that change. A coil is simply a winding of wire used to realize an inductor, so it’s the natural term you’d use for this component. The other options describe different parts: a resistor mainly dissipates energy as heat and doesn’t specifically oppose changes in current; a diode conducts in one direction; a capacitor opposes changes in voltage and stores energy electrostatically instead of magnetically.