Notice that we have the weight of the crane exerting a torque about the front wheels of the same crane. to create a torque, a force must be present, so it would seem that somehow the weight of the crane is exerting a force upon its front wheels. however, the crane is one object, and it follows from newton's laws that an object cannot exert a net force upon itself. this crane seems to be defying newton's laws. what's going on here?

The earth exerts forces on the crane and the load.

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