Assuming that the charges are moving nonrelativistically (v≪c), what can you say about the relationship between the magnitudes of the magnetic and electrostatic forces?\

Assuming that the charges are moving non-relativistically, this means that the velocity is very small as compared to the speed of light. But still moving at this speed they radiate a substantial amount of energy that remains conserved. Although the Kinetic and Potential energy interchange but the overall internal energy remains constant. The magnitude of magnetic and electrostatic forces change according to the change in speed of moving charges.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia