Short Answer
Current reaches 63% of its final value after time τ 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.
τ = L/R; after one time constant, current is at 1 − e⁻¹ ≈ 63% of its final value.
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. Current plateaus immediately
- B. Current reaches 63% of its final value after time τ
- C. Voltage drops to zero at time τ
- D. R cancels L exactly
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.