Question

An infinite line charge produces a field of $18\times 10^{5}N/C$ at a distance of $4cm$ . What is the linear charge density?

• A. $18\mu C/m$
• B. $5\mu C/m$
• C. $4\mu C/m$
• D. $10\mu C/m$

Answer 1

Answer: (C)

For a infinite line charge, $E=\frac{2\lambda }{4\pi {\epsilon }_{0}r}$
$\lambda =E\left(2\pi {\epsilon }_{0}r\right)$
$=\frac{18\times 10^5\times \left(4\times 10^{-2}\right)}{2\times 9\times 10^9}$
$=4\times 10^{-6}C/m$
$=4C/m$