Q. An infinite line charge produces a field of $9 \times 10^{4}\ NC^{- 1}$ at a distance of 2 cm. the linear density is
A) $2 \times 10^{- 7\ }Cm^{- 1}$
B) $10^{- 7\ }Cm^{- 1}$
C) $9 \times 10^{4\ }Cm^{- 1}$
D) None of these
Explanation
(b) $E = \frac{\lambda}{2\pi\varepsilon_{0}r}$
$\lambda = 2\pi\varepsilon_{0}r\ E$
$= \frac{1}{2 \times 9 \times 10^{9}} \times 2 \times 10^{- 2} \times 9 \times 0^{4}$
$= 10^{- 7\ }Cm^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.