You are walking around a large open field. the only objects nearby are two identical speakers set some distance apart, which are both producing sound, in unison with a wavelength of 4 m. as you wander around the field, you notice that at certain locations, the sound you hear is surprisingly loud, while at other is seems unusually quiet. you conclude that you are observing the effects of interference between the two sources of sound waves. indicate what sort of interference woud occur at that point. constructive interference, destructive interference or in between.8 m from each speaker.11 m from one speaker and 7 m from the other.10 m from one speaker and 8 m from the other11 m from one speaker and 14 m from the other20 m from one speaker and 12 m from the other13 m from one speaker and 19 m from the other19 m from one speaker and 14 m from the other

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