Consider a double-slit with a distance between the slits of 0.05 mm and slit width of 0.01 mm. Suppose the screen is a distance of 1 m from the double-slit and light with a wavelength of 600 nm is illuminating the slits. Required:
What is the distance Δdx in mm between the places where the intensity is zero due to the double slit effect?

the electric field is a “force field” around a charged object that illustrates the direction the electric force would push an imaginary 

magnified images possible images can be real = projected onto a screen

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