Question

What is focus?Define it .......​

Answer 1

Answer:

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle

Answer 2

Answer:

a: a point at which rays (as of light, heat, or sound) converge or from which they diverge or appear to diverge

specifically : the point where the geometrical lines or their prolongations conforming to the rays diverging from or converging toward another point intersect and give rise to an image after reflection by a mirror or refraction by a lens or optical system

b: a point of convergence (see CONVERGENCE sense 1) of a beam of particles (such as electrons)

Explanation:

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