"Eyes and Glasses" Common Optical Instruments PPT Courseware

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"Eyes and Glasses" Common Optical Instruments PPT Courseware

New knowledge exploration

1. The structure of the eyeball

The eyeball is like a camera; the lens and cornea work together as a convex lens; the retina is like a film plate on which objects are imaged.

2. Eye adjustment

When looking into the distance: the ciliary body is relaxed, the lens is thin, and the focal length is longer. The light from distant objects just converges on the retina, and people can see distant objects clearly.

When looking closely: the ciliary body shrinks, the lens is thicker, and the focal length is shorter. The light from nearby objects converges on the retina, and people can see nearby objects clearly.

3. Vision correction

If the lens is too thick, the refractive power is too strong, or the eyeball is too long in the front-to-back direction, the light emitted from a certain point in the distance converges in front of the retina and becomes a blurry spot when it reaches the retina.

The lens is too thin, the refractive power is too weak, or the eyeball is too short in the front-to-back direction. After the light emitted from a certain point in the distant object converges on the retina, it is already a blurry spot when it reaches the retina.

Discussion: Prescription of glasses

1. What is lens power?

The reciprocal of focal length, Φ=1/f, unit: m-1

2. What is the power of glasses?

The power of the lens is the value of the lens power multiplied by 100, D=100Φ, unit: degree

3. What do the positive and negative powers of glasses mean?

The positive and negative powers of glasses represent convex lenses and concave lenses respectively.

Class exercises

1. Under normal circumstances, the image received on the retina looks like ______; after adding corrective glasses, the image received on the retina looks like ______. (Fill in "real" or "virtual")

2. Myopia can only see nearby objects. The possible reason is ( )

A. The lens is too thick; B. The lens is too thin;

C. The image is behind the retina; D. The eyeball is too long.

3. The possible reason why hyperopia cannot see nearby objects clearly is ( )

A. The eyeball is too short; B. The lens is too thin;

C. The image is formed in front of the retina; D. The image is formed in front of the retina.

4. There are eye lenses that range from +250 degrees to 200 degrees. What are their focal lengths? Which one should I wear for myopia?

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"Eyes and Glasses" Lenses and Their Applications PPT Courseware 8:

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 8 Learning Objectives 1. What are the main parts of the human eye? 2. How do human eyes see objects? 3. How does the human eye see objects at different distances? 4. What indicates the refractive power of a lens? 5. The formation of myopia..

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 7:

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 7 Think about what you know about your eyes. How do the eyes see these objects? 1. Eyes 1. Structure of the eyeball (1) Lens and cornea: the combined effect is equivalent to A convex lens (2) retina: quite...

"Eyes and Glasses" Lenses and Their Applications PPT Courseware 6:

"Eye and Glasses" Lens and Its Application PPT Courseware 6 Learning Objectives: 1. Understand the structure of the eyeball and how the eye sees objects clearly. 2. Understand the causes of myopia and hyperopia, and know how to correct myopia and hyperopia. 3. Understand the common sense of eye protection. ..

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Update Time: 2024-09-04

This template belongs to Physics courseware Beijing Normal University eighth grade physics volume 2 industry PPT template

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