The electric field just outside a uniformly charged infinite plane with surface charge density σ is
A{'text': 'σ / (2 ε₀)', 'label': 'A'}
B{'text': 'σ / ε₀', 'label': 'B'}
C{'text': 'σ ε₀', 'label': 'C'}
D{'text': '2 σ / ε₀', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'σ / (2 ε₀)', 'label': 'A'}
1. Use Gauss's law with a pillbox spanning the sheet.
2. Field E is perpendicular to the sheet, equal on both sides by symmetry.
3. Flux = 2 E A = σ A / ε₀, so E = σ / (2 ε₀).
4. This is a uniform field, independent of distance from the sheet.
_Source: NCERT Class 12 Physics, Ch 1 "Electric Charges and Fields", §1.11_
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