Question

Assuming potential energy at infinite separation is zero, what is the Potential Energy of a two charge system if the charges are both +10C and are separated by 10m?

• A. $9\times {10}^{9}J$
• B. $9\times {10}^{10}J$
• C. $9\times {10}^{11}J$
• D. None of these

Answer 1

The correct option is B

$9\times {10}^{10}J$

The question has asked us to assume potential energy at infinity to be zero. Then we know by definition, the potential energy of a system of 2 charges at a distance r is given by,
$PE=\frac{kQp}{r}Inthiscase,PE=\frac{9\times {10}^9\times 10\times 10}{10}PE=9\times {10}^{10}J$