Question

Four charges $10^{-5} -2 \times 10^8 ;+3 \times 10^8$ and $2 \times 10^{-8}$ Coulomb are -placed at the four corners of a square,of side 1m the potential at the center of the square is

• A. zero
• B. 360 volt
• C. 180 volt
• D. 360 $\sqrt{2}$ volt

Answer 1

Answer: (D)

Potential at centre $=\frac{ k \left(10^{-8}\right)}{\left(\frac{1}{\sqrt{2}}\right)^{2}}+\frac{ k \left(-2 \times 10^{-8}\right)}{\left(\frac{1}{\sqrt{2}}\right)}+\frac{ k \left(2 \times 10^{-8}\right)}{\left(\frac{1}{\sqrt{2}}\right)}+\frac{ k \left(3 \times 10^{-8}\right)}{\left(\frac{1}{\sqrt{2}}\right)}$
$= k \sqrt{2}\left(10^{-8}+3 \times 10^{-8}\right)$
$=4 \times 10^{-8} \times 9 \times 10^{9} \times \sqrt{2}$
$=360 \sqrt{2}$ volts