Question

The sum of all electromagnetic forces between different particles of a system of charged particles is zero:

• A. only if all the particles are positively charged
• B. only if all the particles are negatively charged
• C. only if half the particles are positively charged and half are negatively charged
• D. irrespective of the signs of the charges

Answer 1

The correct option is D irrespective of the signs of the charges

The net sum of the electromagnetic forces on the system of charged particles is zero and it does not depend on the sign of the charges because the electromagnetic force acting between the charges of the system is a vector quantity and it requires only the direction not the sign of the charge.

Option $D$ is correct.