Mark decided that participants in this study will not be at risk, and therefore, he didn't bother the IRB with his proposal. His study investigates the number of discomfort people is willing to put up with in order to earn a large sum of money. He recruits students by posting ads about a "contest in which you can earn $1000." Everyone who shows up is told that they must do whatever he tells them to do for the next several hours and that the last person to comply will earn the money. He then makes the participants eat disgusting food combinations, rub permanent markers on their own faces, and mail insulting messages to their professors. After two hours he stops the "contest," informs everyone that it was actually an experiment, and explains that there is no prize money. Before participants leave, he gets them to sign an informed consent form to acknowledge that they "were free to leave at any time."

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

i already answered it by 34/s