Short Answer
∇×E = −∂B/∂t 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.
∇×E = −∂B/∂t is the differential form of Faraday's law of electromagnetic induction.
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. ∇·E = ρ/ε₀
- B. ∇·B = 0
- C. ∇×E = −∂B/∂t
- D. ∇×B = μ₀J + μ₀ε₀∂E/∂t
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.