"Eyes and Optical Instruments" Light and Eyes PPT Courseware 3

Description

"Eyes and Optical Instruments" Light and Eyes PPT Courseware 3

1. The structure of the eyeball

Ciliary muscle cornea lens pupil iris

Vitreous Retina Nerves leading to the brain

The combined effect is equivalent to a convex lens

2. How the human eye sees objects

The process of seeing things with the human eye

camera imaging process

The process of seeing objects clearly with the human eye

Optic nerve cells are stimulated by light and transmit this signal to the brain, and we see objects.

Normal eye accommodation - when looking at distant objects

When the ciliary body relaxes, the lens becomes thinner and light from distant objects just converges on the retina, allowing the eye to see distant objects clearly.

Normal eye accommodation—when looking at near objects

When the ciliary body contracts, the lens becomes thicker and its ability to refract light becomes stronger. Light from nearby objects converges on the retina, and the eyes can see nearby objects clearly.

3. Myopia and its correction

Causes of myopia

The lens is too thick (too convex, the focal length is too small), and its refractive power is too strong.

When light reaches the retina, it is a blurry spot.

Light from a distant point converges in front of the retina.

Causes of myopia: The lens is too thick, the refractive power is too strong, or the eyeball is too long in the front-to-back direction. Therefore, light from a distant point converges in front of the retina.

Correction of myopia

Taking advantage of the fact that concave lenses can make light diverge, myopia can be corrected by wearing glasses made of concave lenses.

4. Hyperopia and its correction

Causes of hyperopia

The lens is too thin (too flat, the focal length is too large), the refractive power is too weak, and the image of near objects is behind the retina.

Causes of hyperopia: The lens is too thin, the refractive power is too weak, or the eyeball is too short in the front-to-back direction, so light from a nearby point converges behind the retina.

Correction of hyperopia

Hyperopia can be corrected by wearing glasses (reading glasses) made of convex lenses that use the ability of convex lenses to converge light.

After correction, light from nearby objects converges on the retina.

small experiment

Do it (make your own camera)

Equipment: two paper tubes, convex lens, translucent paper

take a look

Please pick up the camera you made, face it outside the bright window, pull the paper tube, and change the distance between the lens and the translucent paper. What do you see?

Observe and think:

Like zoom out or zoom in? Like standing upright or upside down? Which is greater, image distance or object distance?

Are the image and object on the same side of the convex lens or on both sides?

summary:

Imaging features:

1. The camera produces a shrunken, inverted image.

2. The image distance is smaller than the object distance.

3. The image and object are located on both sides of the convex lens.

camera imaging principle

After the light from the object passes through the camera lens, it is condensed into an image of the object on the film. The film is coated with a light-sensitive substance that undergoes chemical changes after exposure, and the image of the object is recorded on the film. Digital cameras use electronic photosensitive devices and storage devices instead of film as a light screen for imaging and record image information.

The principle of camera

When u>2f, it becomes an inverted and reduced real image.

camera use

When the distance between the person and the camera is u>2f, adjust the focus and aperture. If you want to make the image on the film larger, you should bring the camera closer to the person and move the lens farther away from the film (increase the length of the camera obscura). That is to say, the principle that when the object distance becomes smaller, both the image and the image distance become larger.

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"Eyes and Optical Instruments" Light and Eyes PPT Courseware 2:

"Eye and Optical Instruments" Light and Eyes PPT Courseware 2 Hyperopia Hyperopia is when the lens is too flat, and objects will be imaged behind the retina after being refracted by the lens. Correction: Use a convex lens to first focus the light, and then focus it on the retina through the lens. Myopia, near...

"Eyes and Optical Instruments" Light and Eyes PPT Courseware:

"Eyes and Optical Instruments" Light and Eyes PPT Courseware Learning Objectives 1. Understand the simple structure of the eye and the basic principles of eye vision 2. Understand that cameras are made using the principle that convex lenses can reduce the real image 3. Understand the structures of microscopes, telescopes, etc. and function 4. pass..

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Update Time: 2024-09-08

This template belongs to Physics courseware Guangdong and Shanghai version of eighth grade physics volume one industry PPT template

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