Explanation:

When scattered blue light is seen through a rotating Nicol prism, a variation of intensity with zero minimum intensity is observed. This variation in intensity is a characteristic of plane-polarized light. Let's understand why this is the case.

Scattering of Light:
Scattering of light refers to the process in which light waves get deviated from their original path due to interaction with particles or molecules in the medium through which they pass. When light interacts with small particles or molecules, such as dust particles or molecules in the atmosphere, it scatters in different directions.

Nicol Prism:
A Nicol prism is an optical device that consists of a calcite crystal. It is used to polarize and analyze light. When light passes through a Nicol prism, it splits into two rays, an ordinary ray (o-ray) and an extraordinary ray (e-ray), which travel with different velocities. The Nicol prism is designed to transmit only one of these rays, usually the e-ray, while blocking the other.

Intensity Variation:
When scattered blue light is observed through a rotating Nicol prism, a variation in intensity is observed. This variation occurs because the Nicol prism is capable of transmitting light waves that are polarized in a specific direction. When the scattered light is incident on the Nicol prism, only the light waves that are polarized in the direction allowed by the prism are transmitted, while the rest of the waves are blocked.

If the scattered light is unpolarized, it contains light waves vibrating in all possible directions. As the Nicol prism can transmit only light waves polarized in a specific direction, the intensity of the transmitted light will vary as the Nicol prism is rotated. This variation will have a minimum intensity when the directions of polarization of the scattered light and the prism are perpendicular to each other.

However, in the given scenario, the variation of intensity shows a zero minimum intensity. This implies that the scattered light is plane polarized, meaning it consists of light waves vibrating in a single plane. When the direction of polarization of the scattered light aligns with the allowed direction of the Nicol prism, maximum intensity is transmitted. As the prism is rotated, the intensity decreases and then increases once again when the direction of polarization aligns with the allowed direction.

Therefore, the observed variation of intensity with a zero minimum intensity suggests that the scattered blue light is plane polarized.