Exposure can be affected by , which are slices of glass or gelatin put in front of the lens of the camera or printer to reduce certain frequencies of light reaching the film.

Filters

Explanation:

Filters are transparent or translucent slices of glass or gelatin that are attached in front of the lens of cameras. Filters serve several purposes such as protecting the lens, regulating the amount of light that enters the film, thereby controlling exposure, as well as adding special effects to the images produced.

There are different types of filters that have their unique roles. Examples are the soft focus filter, neutral density filter, polarizing filter, and color balancing filter.

a coal burning power plant

come closer and become far apart and become steam/gas