Question Detail
Question
Parallel plate air capacitor charged to 100V. 2mm dielectric inserted, distance increased by 1.6mm to maintain same V. Dielectric constant?
Correct Answer
Option B is the correct answer.
Detailed Explanation
Initially d, finally d' = d + 1.6 mm. Dielectric thickness 2 mm. With dielectric, effective d_eff = (d' - 2) + 2/κ. For same V and Q, C same: ε₀A/d = ε₀A / [(d' - 2) + 2/κ] → d = (d' - 2) + 2/κ. d' = d + 1.6 → d = (d + 1.6 - 2) + 2/κ = d - 0.4 + 2/κ → 0.4 = 2/κ → κ = 5. Option B.
Hint
Same C → same effective separation.