What do inductors oppose?

What do inductors oppose?

• A. Changes in voltage
• B. Changes in current
• C. Changes in resistance
• D. Changes in frequency

Answer: (B)

Inductors oppose changes in current. They store energy in a magnetic field and produce an induced voltage that acts to keep the current from changing, in accordance with Lenz’s law. The relationship v = L di/dt shows the mechanism: the voltage across the coil is proportional to how quickly the current is changing. If you try to ramp the current up or down quickly, the inductor generates a voltage that fights that change, slowing it down. In DC, once the current stops changing (di/dt = 0), the inductor looks like a short circuit. In AC, the opposition to current changes is quantified by the reactance X_L = ωL, which grows with frequency, making it harder for the current to vary rapidly. So the essential idea is that inductors resist changes in current, not changes in voltage, resistance, or frequency.

Inductors oppose changes in current. They store energy in a magnetic field and produce an induced voltage that acts to keep the current from changing, in accordance with Lenz’s law. The relationship v = L di/dt shows the mechanism: the voltage across the coil is proportional to how quickly the current is changing. If you try to ramp the current up or down quickly, the inductor generates a voltage that fights that change, slowing it down. In DC, once the current stops changing (di/dt = 0), the inductor looks like a short circuit. In AC, the opposition to current changes is quantified by the reactance X_L = ωL, which grows with frequency, making it harder for the current to vary rapidly. So the essential idea is that inductors resist changes in current, not changes in voltage, resistance, or frequency.