What are the functions of concave lens and convex lens?

Concave lens has divergent effect on light. The backward extension line of divergent light will pass through a point on one side of the concave lens, which is called the "focus" of the concave lens and is represented by "F"; The focus of concave lens is virtual focus, one on the left and one on the right, and one * * * has two virtual focuses; The distance from the focal point to the optical center O is called the "focal length" of the concave lens, which is denoted by "f".

Convex lens, which can condense light. The point where light rays converge and intersect at one side of the convex lens is called the "focus" of the convex lens, which is represented by "F"; The focal point of convex lens is real focal point, one on each side, and one * * * has two real focal points; The distance from the focal point to the optical center O is called the "focal length" of the convex lens and is denoted by "f".

Extended data principle

The geometric drawing of concave lens imaging is the same as that of convex lens. From the top of the object, it is also regarded as two straight lines: one parallel to the main optical axis, deflected into divergent light after passing through the concave lens, and returned to the main focus in the opposite direction; The other line passes through the optical center of the lens, and these two straight lines intersect at one point, which is the image of the object.

imaging

The virtual image is reduced by the concave lens, and the object image is on the same side of the lens. 1/u (object distance)+1/v (image distance) = 1/f (lens focal length) lens imaging formula (about symbols: object distance u is positive, ν and f are negative. )。

Reference concave lens _ Baidu Encyclopedia