The phase difference of π radians that you found in the previous part provides a criterion for destructive interference. what phase difference corresponds to completely constructive interference (i. e., the original wave and the shifted wave coincide at all points)?

Answer and Explanation:

The phase difference corresponding to the constructive interference would be zero and that to the destructive interference would also be zero.

At the point when two waves meet so that their peaks line up together, at that point it's called constructive interference. The subsequent wave has a higher sufficiency.  

In destructive interference, the peak of one wave meets the trough of another, and the outcome is a lower amplitude.

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

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it