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

Description

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

learning target

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 and correction of myopia?

6. The formation and correction of hyperopia?

1. The structure of the eyeball:

2. How do human eyes see objects?

The lens and cornea are equivalent to convex lenses, which focus the light from objects on the retina, forming an inverted and reduced real image on the retina.

3. The principle of how the human eye can see distant and near objects clearly:

When the ciliary body relaxes, the lens becomes thinner, allowing light from a distance to converge on the retina, and the eyeball can see distant objects clearly.

When the ciliary body contracts, the lens thickens, allowing light from nearby areas to converge on the retina, allowing the eyeball to see nearby objects clearly.

Compliance test

1. The human eye is a "magic camera". In Figure 1 on the right, _______ is equivalent to the lens of the camera. It can ____________ (fill in "converge" or "divergence") the light on the retina, which is equivalent to The camera’s __________.

2. Figure 2 on the right is a light path diagram when someone looks at a nearby object. From the picture, we can see that he has a narrow eye (choose "myopia" or "hyperopia").

3. In the four pictures shown below, which respectively represent the imaging conditions and correction methods of myopia ( )

4. The glasses someone wears are as shown in Figure 4, then ( )

A． This person's eyes must be nearsighted and

B. This person’s eyes must be farsighted

C. The camera lens is the same type of lens as the glasses

D. The slide projector lens is the same type of lens as the glasses

Prescription of glasses

The length of the lens focal length f indicates the size of the refractive power. The shorter the focal length, the greater the refractive power. Usually the reciprocal of the focal length of the lens is called the lens power, which is represented by Φ, that is, Φ = 1/f, unit: m-1

Example: If the focal length of a lens is 0.5m, its power is: Φ =1/f=2m-1

If hyperopia is severe, the refractive power of the convex lens of the glasses should be larger, and the lens power should be larger. The power of eyeglass lenses is usually the power of the lens multiplied by 100. For example: the focal length is 0.5 meters, the power is 2m-1, and the power of the glasses is 200 degrees. If it is a 100-degree lens, what is its focal length?

The power of convex lenses (lenses for hyperopia) is positive;

The power of concave lenses (lenses for myopia) is negative.

answer the following questions

1. Between the +300 degree and -200 degree spectacle lenses, which one is the hyperopia lens? What is their power?

Solution: +300 degrees is a hyperopia lens.

From X=100 Φ we can get:

Φ＝X/100＝300/100＝3（m－1）

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For more information about the PPT courseware "Lens and Its Applications in Eyes and Glasses", please click the "Lens and Its Applications ppt Eyes and Glasses ppt" tag.

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Update Time: 2024-10-05

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