When you look out your window and see a skateboarder in front of your house and 2 min later you look out and see her several houses away you can use this information to describe her

this information describes her as skateboarding down the street.

The skateboarder's speed could have changed in the two minutes that you weren't looking out the window. Her velocity could have changed too, as well as her acceleration. The only thing that you know for a fact is her change in position.

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