What is a collection of rays diverging from or converging on a single point called?

The correct answer, which describes a collection of rays diverging from or converging on a single point, is referred to as a pencil. In optics, a pencil of light is defined as a group of rays that travel together through space, and it can represent either converging or diverging rays focused on a single point.

When dealing with light rays, it's important to understand the significance of how they interact with optical systems. A pencil can help in analyzing how light spreads out or converges, which is essential in many applications, such as designing lenses or optical instruments.

Lenses, while they manage and manipulate light rays effectively, do not themselves define a collection of rays but rather are the mediums that cause them to diverge or converge. A beam generally refers to a more extensive collection of light rays that can be uniform or variously focused but doesn’t specifically pertain to the convergence or divergence around a single point. Conversely, a wavefront characterizes the surface over which an optical wave has a constant phase, which is a broader concept related to the propagation of light rather than a specific collection of rays focused on a point.

Thus, "pencil" is the most appropriate term for describing a specific arrangement of rays converging or diverging