Short Answer
Frequency increases is the best answer.
Electromagnetism questions become manageable once you separate source, field, potential, current, and force. Most wrong answers mix those layers together or ignore direction.
Skin depth δ = √(2/ωμσ) — at higher frequencies, current is confined to a thinner surface layer.
Why This Answer Is Correct
This is a Medium-level question in Electromagnetism. The prompt is really testing whether you can connect the concept to its defining physical relationship instead of picking a nearby-but-wrong term.
Keep charge, field, potential, and current distinct. That single habit fixes a large fraction of electromagnetism errors.
Choices At A Glance
- A. Frequency decreases
- B. Conductivity decreases
- C. Frequency increases
- D. Permeability decreases
When similar options appear on an exam, eliminate the ones that break the core law, use the wrong units, or confuse a definition with a consequence.
Topic Snapshot
Topic: Electromagnetism
Difficulty: Medium
Best next move: Re-state the governing law in your own words, then solve one more example from the same topic before moving on.