Increasing frequency across an inductor affects what property according to the material?

Increasing frequency across an inductor affects what property according to the material?

• A. The inductance increases
• B. The coil resistance increases
• C. The current amplitude decreases to zero
• D. The energy stored becomes infinite

Answer: (A)

The property that changes with frequency in this context is the inductance. In coils that use magnetic core materials, the core’s magnetic permeability can vary with frequency, so the effective inductance can increase as frequency rises. When inductance goes up, the coil’s ability to store magnetic energy also increases (since energy is ½LI²), and the impedance seen by the source, which is ωL, grows accordingly. That’s why, according to the material, increasing frequency can lead to higher inductance. The other options don’t reflect a material-driven change in the same way: coil resistance can rise with frequency due to losses, but that’s a separate effect from the inductance itself; current amplitude wouldn’t necessarily drop to zero just from frequency alone; and energy stored wouldn’t become infinite.

The property that changes with frequency in this context is the inductance. In coils that use magnetic core materials, the core’s magnetic permeability can vary with frequency, so the effective inductance can increase as frequency rises. When inductance goes up, the coil’s ability to store magnetic energy also increases (since energy is ½LI²), and the impedance seen by the source, which is ωL, grows accordingly. That’s why, according to the material, increasing frequency can lead to higher inductance.

The other options don’t reflect a material-driven change in the same way: coil resistance can rise with frequency due to losses, but that’s a separate effect from the inductance itself; current amplitude wouldn’t necessarily drop to zero just from frequency alone; and energy stored wouldn’t become infinite.