Question

Find the electric field strength due to 5$\mu$C of charge at a point 30 m away from it in air

• A. 25 NC${}^{-1}$
• B. 100 NC${}^{-1}$
• C. 50 NC${}^{-1}$
• D. 150 NC${}^{-1}$

Answer 1

Answer: (C)

50 NC${}^{-1}$

Using formula, $E=\frac{1}{4\pi {\epsilon }_o}\frac{q}{r^2}$

Here, $q=5\times {10}^{-6}C$

$r=30m$

So, $E=9\times {10}^9\times \frac{5\times {10}^{-6}}{(30{)}^2}$

$=5\times {10}^3\times {10}^{-2}$

$=5\times 10=50N{C}^{-1}$