The fact that you can see interference colors in an oil slick on a puddle gives evidence that the oll film a) has two reflecting surfaces b) is thin c) causes only 1 phase shift d) all of these e) two of these

Option A

Explanation:

The interference color in an oil slick on a puddle results from the interference  caused as a result of reflection of light waves from the top as well as from the bottom surface of the oil slick.

This causes a disparity in the path of light reflecting from the surfaces and hence the sunlight is a band of seven colors, i.e., VIBGYOR, the disparities in the path results in constructive interference of the light rays which enables us to see interference colors in an oil slick.

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

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.