What device projects a ray of light through a lens to display an image onto a surface?

A projector is a device designed specifically to take an image or video signal and project it onto a larger surface, typically a screen or wall, using a lens. The core function of a projector involves projecting a ray of light through its internal lens system, which magnifies and focuses the image, allowing for a clear display on the chosen surface. This is especially valuable in settings like classrooms, conference rooms, or home theaters, where sharing visual content with a larger audience is necessary.

In contrast, a monitor, TV, and smartboard serve different functions. A monitor and TV are primarily designed to display images directly, often for individual or small group viewing, without the need for projection. A smartboard is an interactive display that may combine features of both a whiteboard and a touchscreen, allowing for collaboration but does not project images in the same manner as a projector does. Thus, the projector is uniquely suited for projecting larger images onto surfaces, which is why it is recognized as the correct answer.