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

Description

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

think about it

Do you know your own eyes?

How do the eyes see these objects?

1. Eyes

1. The structure of the eyeball

(1) Lens and cornea: working together is equivalent to a convex lens

(2) Retina: equivalent to light screen

(3) Ciliary body: adjust the curvature of the lens (the ciliary body relaxes and the lens becomes thinner)

(4) Iris: adjust pupil size

2. The principle of human eyes seeing distant and near objects clearly

Distant: The ciliary body relaxes, the lens becomes thinner, and the light from the distance just converges on the retina.

Near: The ciliary body shrinks, the lens thickens, and the light from near just converges on the retina.

①The farthest place that normal eyes can see is called far point. Where is the farthest place that you can see?

②The closest place that normal eyes can see is called the near point. Where is the farthest place that you can see?

③What is the distance at which normal eyes can observe nearby objects most clearly without fatigue?

3. The far point of a normal eye is at infinity, and the near point is about 10cm.

4. The distance at which normal eyes can observe nearby objects clearly without fatigue is about 25cm. This distance is called photopic distance.

Practice in class:

1. The human eye is a kind of "magical camera". In the picture below, _______ is equivalent to the lens of the camera. It can _____ (fill in "converge" or "divergence") the light.

On the retina, the retina is equivalent to the _____ of a camera.

2. After the light is refracted by the lens of the eyeball, it can be imaged on the retina. The picture below is a normal eyeball imaging model designed by Xiaoliang. The following description is correct ( )

A． Convex lens is equivalent to retina

B． Candles are equivalent to lenses

C. Convex lens is equivalent to lens

D. The light screen is equivalent to the lens

3. The eye is a convex lens with "variable focal length". It changes the thickness of the lens through ________. When the ciliary body ______, the lens becomes ____, and the light from distant objects converges on the retina. Eyes see distant objects. When the ciliary body _____, the lens becomes ____, light from nearby objects converges on the retina, and the eye sees nearby objects.

2. Myopia and its correction

1. Symptoms: Can see close objects clearly, but cannot see distant objects clearly

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

3. Correction: Use the divergent effect of concave lenses on light and wear myopia glasses made of concave lenses.

3. Hyperopia and its correction

1. Symptoms: Can see distant objects clearly, but cannot see close objects clearly

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

3. Correction: Make use of the light converging effect of convex lenses and wear hyperopia glasses made of convex lenses.

Practice in class:

1. As shown in Figure A, the optical path of light from a distance passes through the refractive system of someone's eyeball. Which of the following is correct regarding the judgment of the person's nearsightedness and nearsightedness and the selection of spectacle lenses required for correction ( )

A. Myopia; B

B. Hyperopia; B

C. Myopia; C

D. Hyperopia; C

2. Xiao Ming’s grandfather and father are both presbyopic. Grandpa’s presbyopia is more severe, while Xiao Ming’s mother is myopic. The three pairs of glasses they use are placed on the newspaper, as shown in the picture. Now Dad wants to read a book and asks Xiao Ming to hand the glasses to him. Xiao Ming should take the pair in the picture _____.

4. The prescription of glasses

(1) Measuring focal length f, unit is meter

(2) Calculating power: the reciprocal of focal length, Φ=1/f, unit: m-1

(3) Lens power: lens power multiplied by 100, D=100Φ, unit: degree

The power of the lens D=100Φ =1/f×100

(4) The power of farsighted glasses (convex lenses) is expressed as a positive number, and the power of myopia glasses (concave lenses) is expressed as a negative number.

Classroom consolidation:

1. Patients with myopia need to wear glasses made of ________ because the lens has a _____ effect on light. People with hyperopia need to wear glasses made of _____ because the lens has a _____ effect on light.

2. The human eye is like a camera. For people with normal vision, objects are imaged on the retina through the lens. For myopia ( )

A． The image is in front of the retina and needs to be corrected by wearing a convex lens

B． The image is in front of the retina and needs to be corrected by wearing a concave lens

C. The image is behind the retina and needs to be corrected by wearing a convex lens

D. The image is behind the retina and needs to be corrected by wearing a concave lens.

3. Teacher Gao was correcting homework while wearing glasses. She heard a student calling her from a distance. In order to see the student clearly, Teacher Gao immediately took off her glasses and greeted the student. Which of the following statements is correct ( )

A. Teacher Gao is short-sighted

B. When Teacher Gao looks at nearby objects without wearing glasses, the image appears in front of the retina.

C. Teacher Gao’s eye lens is too thick

D. The lenses of the glasses worn by Teacher Gao are convex lenses

What did you gain?

①Principle of eye imaging (camera)

②Causes and correction of myopia (concave)

③Causes and correction of hyperopia (convexity)

④The degree of the eyes

Keywords: Lens and its application teaching courseware, Eyes and glasses teaching courseware, Lujiao edition eighth grade physics PPT courseware download, eighth grade physics slide courseware download, Lens and its application PPT courseware download, Eyes and glasses PPT courseware download, .PPT format;

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.

"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 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. ..

"Eyes and Glasses" Common Optical Instruments PPT Courseware 4:

"Eyes and Glasses" Common Optical Instruments PPT Courseware 4 1. The structure of the eye and imaging principles 1. The structure of the eyeball ① What does the structure of the eyeball look like what we have learned before? ②What is the equivalent of the combined effect of the lens and the cornea? What is the equivalent of retina? Come..

File Info

Update Time: 2024-10-05

This template belongs to Physics courseware Lu Jiao edition eighth grade physics volume 1 industry PPT template

Preview