A filter of 2 mm of aluminum is effective in absorbing which type of radiation?

The effectiveness of a 2 mm aluminum filter in absorbing radiation can be best understood through the types of radiation that it interacts with based on their penetrating power.

Alpha particles are relatively heavy and carry a positive charge. They are significantly less penetrating than other forms of radiation and can be stopped by a sheet of paper or even the outer layer of human skin. As a result, while aluminum can absorb alpha particles, a particle filter of this thickness is not necessary for their attenuation.

Soft, or less penetrating, radiation generally refers to lower-energy radiation, such as alpha particles, beta particles with lower energy, and certain X-rays. The 2 mm thickness of aluminum is particularly adept at attenuating softer forms of radiation due to its atomic structure and density, which allows it to effectively absorb and scatter these types of less energetic rays.

High-energy radiation, such as gamma rays and higher-energy X-rays, are much more penetrating and require much denser materials, like lead, for effective shielding. Therefore, a filter of 2 mm aluminum would not be efficient in absorbing high-energy radiation.

The choice of soft or less-penetrating radiation as the correct answer highlights the aluminum filter's specific capability to absorb types of radiation that have a low amount of penetrating