NEET Solved Paper 2019 Question 20

Question: 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? [NEET 5-5-2019]

Options:

A) $ \frac{\lambda }{\pi {\in_0}R}N/C $

B) $ \frac{\lambda }{2\pi {\in_0}R}N/C $

C) Zero

D) $ \frac{2\lambda }{\pi {\in_0}R}N/C $

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Answer:

Correct Answer: B

Solution:

  • At $ P,E=E _1+E _2=\frac{2k{\lambda_1}}{R}+\frac{2k{\lambda_2}}{R} $
    $ \therefore {\lambda_1}={\lambda_2} $ $ \frac{4K\lambda }{R}=\frac{\lambda }{\pi {\in_0}R} $