What is the best description of the destructive interference of light?

a. a mechanical wave meets an electromagnetic wave

b. two waves have displaced in opposite directions

c. two waves have the same direction of displacement

d. a longitudinal wave meets a transverse light wave

(it is b)

B. Two waves have displaced in opposite directions

Explanation:

Interference occurs when two waves meet at a point in space. When this occurs, two extreme conditions can occur:

- if the two waves are in phase (=displacement in the same direction), the amplitude of the resultant wave is equal to the sum of the amplitudes of the two waves:

A = A1 + A2

and this condition is called constructive interference

- if the two waves are in anti-phase (=displacement in opposite directions), the amplitude of the resultant wave is equal to the difference of the amplitudes of the two waves:

A = |A1 - A2|

and this condition is called destructive interference. Note that if A1=A2, the amplitude of the resultant wave is zero.

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