What will happen to the mass of a charged body?

The mass of a charged body will not change due to the charge. The mass of an object is a fundamental property of the object, a numerical measure of its inertia and fundamental to the Newton's laws of motion. Charge is a property that causes it to experience a force when placed in an electromagnetic field. Therefore, charging a body does not change its mass. However, if we consider Einstein's mass-energy equivalence principle (E=mc^2), adding energy (including the energy to add a charge) to a system will increase its mass. But this increase is usually too small to be measured with current technology when we are talking about charging objects.