What is the difference between a convex lens and a concave lens

Concave-convex lens is an important and error-prone knowledge point in junior high school physical optical imaging. Because there are many imaging laws involved in the two, students often confuse them. In this article, we will sort out the structure and imaging of concave and convex lenses. And the difference in use, etc., to help students learn better.

【Definition of convex lens】

Convex lenses are made according to the principle of refraction of light. A convex lens is a lens that is thicker in the center and thinner at the edges. Convex lenses are divided into biconvex, plano-convex and concave-convex (or positive meniscus) forms. Convex lenses have the function of converging light, so they are also called converging lenses. Thicker convex lenses have functions such as telescopic and converging, which are related to the thickness of the lens. .

【Definition of Concave Lens

A concave lens is also called a negative spherical lens. The middle of the lens is thin and the edge is thick and concave, so it is also called a concave lens. Concave lenses have a divergent effect on light. Myopia glasses are concave lenses.

【The difference between the two】

First, the structure is different

The convex lens is composed of a transparent mirror body ground into a spherical surface on both sides;

A concave mirror consists of a mirror body that is concave on one side and opaque on the other

Second, the imaging properties are different

Convex lens is refraction imaging, the image can be positive, inverted; virtual, real; zoom, zoom. Concentrate light

A concave mirror is a reflection imaging that can form an inverted or enlarged real image, or an upright enlarged virtual image. The astigmatism lens (including the convex lens) is an instrument that allows light to pass through and is refracted and imaged after the light is refracted. The light obeys the law of refraction.

3. Different effects on light

Convex lenses mainly focus on light

The concave lens mainly scatters the light

Four, different imaging

The convex lens can form upright enlarged virtual images, inverted enlarged real images, inverted large real images, and inverted inverted real images;

A concave lens can only form an upright reduced virtual image

5. Different uses

Convex lenses are used for hyperopia glasses, and convex lenses can be used for magnifying glasses, glasses worn by people with presbyopia and hyperopia, cameras, movie projectors, slide projectors, microscopes, and telescope lenses.

Concave lenses are used in myopia glasses.