What principle of magnification does a CCTV use for reading?

The principle of magnification that a CCTV (closed-circuit television) system uses for reading is relative size magnification. This principle refers to how the system visually enlarges the images of text or objects being captured, making them appear larger to the user.

In a CCTV, the camera captures the text, and the video feed is displayed on a screen at a comfortable distance for the user, which enhances the size of the visual information. This makes it easier for individuals with low vision to read or view text and intricate details. The relative size magnification effectively allows the user to perceive smaller characters as larger ones, thereby assisting in readability.

While other magnification principles like rated magnification and equivalent magnification have their specific applications in optical systems, they are not the primary concepts utilized by CCTVs for reading tasks. Relative distance magnification involves changing the distance from which an object is viewed to increase its apparent size, but in the context of CCTVs, the focus is on enhancing the size of the image through electronic means rather than solely adjusting distance. Thus, relative size magnification is the most applicable principle for understanding how CCTVs assist with reading.