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An infinite uniform line of linear charge density λ produces an electric field at perpendicular distance r equal to:
Aλ / (2πε₀ r)
Bλ / (4πε₀ r)
Cλ / (πε₀ r²)
Dλ ε₀ / r
Answer & Solution
Correct answer: A. λ / (2πε₀ r)
1. By Gauss's law with a cylindrical surface of radius r and length L:
2. E · 2π r L = (λ L) / ε₀.
3. E = λ / (2π ε₀ r).
4. Note 1/r dependence (not 1/r² — that's a point charge).
_Source: NCERT Class 12 Physics Ch 1 §1.10 Applications of Gauss's Law_
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