Which property is affected by a diverging lens?

The property affected by a diverging lens is the focal length. A diverging lens, which is typically concave in shape, causes light rays that are parallel to its principal axis to spread out or diverge. The focal length of a diverging lens is defined as the distance from the lens to the point where the light rays appear to diverge from a common point (the focal point).

In a diverging lens, this focal point is virtual, meaning the light rays do not actually converge at this point; instead, they appear to stem from it when traced back. The focal length is a significant parameter because it determines how strongly the lens will bend the light rays, influencing the image produced by the lens.

While the other options might relate to optical properties, they do not directly correspond to the fundamental effect of a diverging lens. Brightness of light and color temperature could be influenced by other factors in a broader optical system, and the wavelength of light depends on the light source itself rather than being modified by the lens. Thus, the focal length is the key characteristic that is specifically altered by the use of a diverging lens.