alleryThe electric field of an infinite line of charge with linear charge density λ at perpendicular distance r is
AE = λ / (ε₀ r²)
BE = λ / (4π ε₀ r²)
CE = λ r / (2π ε₀)
DE = λ / (2π ε₀ r)
Answer & Solution
Correct answer: D. E = λ / (2π ε₀ r)
1. Apply Gauss's law with a cylindrical Gaussian surface coaxial with the line.
2. Field E is radial and uniform on the cylinder side, zero on end caps.
3. Flux = E × 2π r L = λL / ε₀, giving E = λ / (2π ε₀ r).
4. Field falls off as 1/r, characteristic of the line-charge geometry.
_Source: syllabus Physics, Ch 1 "Electric Charges and Fields", §1.10_
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