Myopia is a condition of the eye where the crystalline lens focuses the light rays to a position between the lens and the retina. to correct for this condition, a thin lens is placed in front of the eye that will to focus light on the retina. the type of lens required is:

concave lens

Explanation:

Myopia is a condition of the eye where someone can only see near distant object clearly but not far distant object.

Myopia is corrected using concave lens (diverging) in order to diverge the rays entering the eye thereby allowing the rays to be focused properly on the retina.

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