Question

If the charges are in equilibrium, what is the net force on the 1C charge on the right top corner if the side of the square is 1m and if they are in vacuum?

• A. $9\times {10}^9$ N
• B. $0N$
• C. $18\times {10}^9$ N
• D. $9\sqrt{2}\times {10}^9$ N

Answer 1

The correct option is B

$0N$

Newton's laws tell us that whenever a body is in equilibrium, the net force on it must be zero.
Even though there are net electrostatic forces on each charge, some other force is holding it in place for it to be in equilibrium.
Hence net external force is zero.