Q. A point charge$q$ produces an electric field of magnitude 2 NC$^{-1}$ at a point distance 0.25 m from it. What is the value of charge?
A) 1.39$\times 10^{- 11\ }$C
B) 1.39$\times 10^{11\ }$C
C) 13.9$\times 10^{- 11\ }$C
D) 13.9$\times 10^{11\ }$C
Explanation
(a) $\therefore E = \frac{1}{4\pi\varepsilon_{0}r^{\begin{array}{r}
2 \\
\
\end{array}}}$
$q = 4\pi\varepsilon_{0}r^{2}E$
$= \frac{(0.25)^{2} \times 2}{9 \times 10^{9}} = 1.39 \times 10^{- 11}$ C$\ $
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.