Please explain the principles of concave and convex lenses, and please don't repeat them! Thanks!

A concave lens, also known as a negative spherical lens, has a thin center and thick periphery and is concave in shape, hence the name concave lens. Concave lenses have a diffusing effect on light. Parallel rays of light through the concave spherical lens deflection, light dispersion, become dispersed rays, it is impossible to form a real focus, along the reverse extension of the dispersed rays of light, on the same side of the projected light intersected at point F, the formation of a virtual focus.?

The geometric drawing of concave lens imaging is the same as that of convex lenses in principle. From the top of the object also as two straight lines: one parallel to the main optical axis, after the concave lens deflection for the diverging light, the refracted light in the opposite direction to return to the main focus; the other through the optical center of the lens, these two straight lines intersected at a point, which is the image of the object.

The geometry of concave lens imaging is the same as the convex lens.

Concave lenses are always smaller than the image of the object, upright virtual image, concave lenses are mainly used to correct myopia.

A transparent body, spherical on both sides or spherical on one side and flat on the other, with a thin center part, is called a concave lens. When used in light-sparing media, it can diffuse the incident beam, so it is also known as diffusion lenses. Also known as negative lens because of its negative focal length. For thin concave lenses, the imaging formula, lateral magnification formula and the law of symbols are the same as convex lenses.

There are three types of biconcave, plano-concave, and convex-concave lenses. The line between the centers of curvature of the two surfaces is called the principal axis, and its central point O is called the optical center. Through the optical center of the light, no matter where it comes from are not refracted. Parallel to the main axis of the beam, shining on the concave lens refracted to the four sides of the dispersion, against the direction of its dispersion of the extension of the line, will be on the same side as the source of light at a point F, the refracted rays of light from the F point, this point is called the virtual focal point. There is one on each side of the lens. A concave lens is also known as a diverging lens. The focal length of a concave lens is the distance from the focal point to the center of the lens. The larger the radius of curvature of the spherical surface of the lens, the longer the focal length, such as a thin lens, the focal length of the two sides of the lens is equal.

The image made by a concave lens is always smaller than that of the object

Convex lens (convex?lens)

Convex lenses are made according to the principle of refraction of light. Convex lenses are lenses with a thicker central portion. Convex lenses are divided into biconvex, plano-convex and concave-convex (or positive meniscus) and other forms, thin convex lenses have a converging effect, so it is also known as a converging lens, thicker convex lenses is expected to be far away, convergence and other roles, which is related to the thickness of the lens.

Parallel rays of light (such as sunlight) parallel to the axis (convex lens two spherical spherical center of the line known as the main optical axis of this lens) into the convex lens, the light in the lens on both sides after two refractions, concentrated in the axis of a point, this point is called the focal point of the convex lens (notation F, English: focus), convex lens in the mirror on each side of the focal point, such as thin lenses, the two focal points to the center of the lens, the distance is roughly equal. In the case of a thin lens, the distance between the two focal points and the center of the lens is approximately equal. The focal length of a convex lens is the distance from the focal point to the center of the lens, usually expressed as f. The more the spherical radius of the convex lens, the more the focal length of the lens. The smaller the spherical radius of a convex lens, the shorter the focal length. Convex lenses can be used for magnifying glasses, presbyopia and farsighted people wear glasses, cameras, movie projectors, microscopes, telescopes lens (lens) and so on.

Lens imaging meets the lens imaging formula: ?

1/u (object distance) + 1/v (image distance) = 1/f (focal length of the lens)?

(Positive and negative signs: 1/u is positive when the object is real, and negative when the object is virtual. Similarly, when the image is a real image, 1/v is a positive sign, and when the image is an imaginary image, 1/v is a negative sign)

Convex and concave lenses are distinguished by:

1. touching method (a concave lens is thin in the middle and thick at the edge, and a convex lens is thick in the middle and thin at the edge)

2. focusing method (injecting a parallel light, which converges on a convex lens, and disperses on a concave lens)

3. looking with the eyes (put the lens under the word and see whether the illuminated word is enlarged or not). See whether the word is enlarged or reduced after illumination)

[edit]Imaging with a convex lens

The object is placed out of focus, and becomes an inverted solid image on the other side of the convex lens, and there are three kinds of solid images, namely, reduced, equidistant, and enlarged. The smaller the object distance, the larger the image distance, the larger the real image. The object is placed within the focus, in the same side of the convex lens into an upright magnified virtual image. The larger the object distance, the larger the image distance, the larger the virtual image.

In optics, by the actual light convergence into the image, known as the real image, can use the light screen to undertake; on the contrary, it is known as the virtual image, can only be felt by the eye. Experienced physics teacher, in telling the difference between the real image and the virtual image, will often mention such a distinction: "real image are inverted, while the virtual image are upright." The so-called "upright" and "inverted", of course, is relative to the original object.

The three types of virtual images made by plane mirrors, convex mirrors, and concave lenses are all orthogonal, while the real images made by concave mirrors and convex lenses, as well as the real image made by aperture imaging, are all inverted, without exception. Of course, concave mirrors and convex lenses can also form virtual images, and the two virtual images they make, again, are in the state of being upright.

So is the image made by the human eye a real image or an imaginary image? We know that the structure of the human eye is equivalent to a convex lens, then the image of the external object on the retina must be a real image. According to the empirical rule above, it seems that the object image on the retina should be inverted. But any object that we normally see is clearly upright. This conflict with the "rule of thumb" actually involves cortical adjustments and the influence of life experience.

When the distance between the object and the convex lens is greater than the focal length of the lens, the object into an inverted image, when the object from a distance closer to the lens, the image gradually larger, the image of the distance to the lens is gradually larger; when the distance between the object and the lens is less than the focal length of the object into an enlarged image, the image is not the actual refracted rays of the point of convergence, but rather, the intersection of the extension line of their reversal, the use of the screen can not be received, it is the image of the virtual. Can be compared with the imaginary image made by the plane mirror (can not be received with the light screen, only with the eyes to see).

When the distance between the object and the lens is greater than the focal length, the object into an inverted image, this image is like a candle to the convex lens light through the convex lens convergence and become, is the actual light convergence point, can be received with a light screen, is a real image. When the distance between the object and the lens is less than the focal length, the object becomes an orthogonal virtual image.?

Difference with convex lens?

I.

I. Different structure?

A convex lens consists of a transparent mirror with two surfaces ground into a sphere?

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

ii. How do they act on light?

Convex lenses mainly converge light rays?

Concave mirrors mainly diffuse light?

iii. What is the nature of the image?

A convex lens is a refractive image?

Concave mirrors are reflecting imagesConvex lenses are refracting images? The image can be? positive, inverted; virtual, real; zoom in, zoom out. It concentrates the light?

Concave mirrors are reflective? Can only become a reduced orthostatic image. Diffuse the role of the lens (including convex lenses) is to make the light through, the use of light after the folding of the image of the instrument, light respect abide by the law of refraction. Mirrors (including convex mirrors) is not to make the light through, but reflected back to the imaging instrument, the light to comply with the law of reflection.

Convex lenses can be inverted magnified, equal size, reduced solid image or orthogonal magnified virtual image. Parallel light can be converged at the focal point, but also can be refracted into parallel light from the focal point. Convex mirror can only become an orthogonal reduced virtual image, mainly used to expand the field of view.

(1) beyond the twofold focal length, inverted reduced solid image;?

One to two times the focal length, inverted magnification of the real image;?

Within one focal length, orthogonal magnification of the virtual image;?

A real image of the object and image on opposite sides of the convex lens, and an imaginary image on the same side of the convex lens.

(2)

One focal length divided into real and imaginary?

Is the double focal length the same as the double focal length?

Table of imaging laws of a convex lens

Distance from the object to the lens u? Size of the image? image size? image inversion? Image's virtual reality? Distance from image to lens v?Examples of applications?

u>2f,? Reduction? Inverted? Real image?2f>v>f?Camera

u=2f,? equal size? inverted? solid image?v=2f?

2f>u>f?magnified? inverted? solid image?v>2f?projector, slide projector, projector

u=f?none? no? None? Parallel light source: searchlight

u<f?magnification? Orthostatic? Virtual image? None? virtual image on the same side of the object? Magnifying glass

(3) convex lens imaging also satisfy 1/v + 1/u = 1/f

The use of special light of the lens as a lens imaging light path:

(1), the object is outside the 2 times the focal length

(2), the object is between the 2 times the focal length and the 1 times the focal length

(3), the object is in the focal point

(4), the light path of the imaging of a concave lens

Experimental study The imaging law of a convex lens is: when the object distance is within one times the focal length, an orthogonal, magnified virtual image is obtained; between one times the focal length and two times the focal length an inverted, magnified solid image is obtained; outside the two times the focal length, an inverted, reduced solid image is obtained.?

The experiment is to study to confirm this law. In the experiment, there is the following table:?

The object? Distance? u? Nature of image? Position of the image?

Orthostatic or inverted? Magnification or reduction of the virtual or real image? Same side as object and opposite side of image distance v?

u>2f?Inverted and reduced? solid image anisotropic?f<v<2f?

u=2f?inverted equal? Real image anisotropic?v=2f?In this case the distance between the object and the image is the minimum, both 4 times the focal length.

f<u<2f?Inverted magnification? Real image anisotropic?v>2f?

u=f?No image, since v=infinity (parallel, therefore infinite)

u<f?Orthogonal? Magnified? Imaginary image? same side? u,v same side?

This is the table designed to confirm that law. In fact, the lens image satisfies the lens image formula: ?

1/u (object distance) + 1/v (image distance) = 1/f (focal length of the lens)

Camera is the use of the imaging law of convex lenses

The lens is a convex lens, the scene to be photographed is the object, the film is the screen

Light irradiated on the object through diffuse reflection through the convex lens will be the image of the object into the final film

The film is coated with a layer of light-sensitive The film is coated with a layer of light-sensitive substances, which undergoes a chemical change after exposure, the image of the object is recorded on the film

As for the object distance, the relationship between the image distance and the imaging law of the convex lens is exactly the same

Objects close to the image is more and more far away, more and more, and then finally on the same side of the image into the virtual image.

In addition, when the object is at infinity, the image can be approximated as being at the focal point. (Because of this, dumb cameras don't need to be focused.)

As the object moves away from the convex lens, the image moves away from the convex lens. Wherever the object goes, the image goes.

When the object moves from infinity to 2F from the image, the object moves faster than the image.