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Topic: Electric field, field lines, field of point charge· Electrostatics

Two parallel infinite line charges with linear charge densities +λ C/m and -λ C/m are placed at a distance of 2R in free space. What is the electric field mid-way between the two line charges ?

1. zero

2. \(\frac{2\lambda}{\pi\epsilon_0 R}\) N/C

3. \(\frac{\lambda}{\pi\epsilon_0 R}\) N/C

4. \(\frac{\lambda}{2\pi\epsilon_0 R}\) N/C

1 answer

Best answer

Answer: 3. \(\frac{\lambda}{\pi\epsilon_0 R}\) N/C

The field of an infinite line charge at distance \(r\) is \(E=\dfrac{\lambda}{2\pi\epsilon_0r}\).

Midway, \(r=R\) for each line. The +\(\lambda\) line pushes away from itself, and the \(-\lambda\) line pulls towards itself. Both fields point the same way, so they add.

\(E=2\times\dfrac{\lambda}{2\pi\epsilon_0R}=\dfrac{\lambda}{\pi\epsilon_0R}\).

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report
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