Question

Three charges each of $+4\mu C$ are the corners B, C, D of a square ABCD of side 1m. The electric field at the centre ‘O’ of the square is

• A. $7.2\times {10}^{4}N/CtowardsA$
• B. $7.2\times {10}^{4}N/CtowardsC$
• C. $3.6\times {10}^{4}N/CtowardsA$
• D. $3.6\times {10}^{4}N/CtowardsC$

Answer 1

The correct option is A $7.2\times {10}^{4}N/CtowardsA$

$E_c=\frac{1}{4\pi {ϵ}_0}\frac{q}{r^2}$
$=9\times {10}^9\times \frac{4\times {10}^{-6}}{{\left(\frac{1}{\sqrt{2}}\right)}^2}$
$=9\times 8\times {10}^3$
$=7.2\times {10}^{4}N/C$
Towards A