"Eyes and Glasses" Lenses and Their Applications PPT Courseware 5

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"Eyes and Glasses" Lenses and Their Applications PPT Courseware 5

1. Two convex lenses with the same diameter have focal lengths of 8cm and 16cm respectively. Which lens deflects light more? What conclusions can you draw from this? If you examine the concavity and convexity of the lens again, what other conclusions can you draw?

Conclusion: The more convex the convex lens, the stronger the refractive power!

2.The following optical components are available:

A. Plane mirror B. Concave mirror C. Convex mirror D. Convex lens E. Concave lens F. Myopia lens G. Hyperopia lens H. Triangular prism

Please choose the appropriate serial number and fill in the horizontal line.

⑴ Those that have a divergent effect on light are ( )

⑵There are two focuses ( )

⑶There is only one focus ( )

⑷Those who work using the law of light reflection are ( )

⑸Those who work using the law of refraction of light are ( )

⑹ Those who can decompose sunlight into various colors of light are ( )

eye structure

The structure of the human eye is very similar to that of a camera: the cornea and lens are equivalent to the convex lens of the camera, the pupil is equivalent to the aperture, the choroid is equivalent to the camera obscura, and the retina is equivalent to the film.

Ask a question:

When looking at objects at different distances with your eyes, the images are all formed on the retina, that is, the distance between the image and the lens remains unchanged. Doesn't this contradict the law of lens imaging? How are the eyes adjusted?

Normal eye accommodation:

The eye changes the shape of the lens through the ciliary body: when the ciliary body relaxes, the lens is relatively thin, and the light from distant objects just converges on the retina, and the eyeball can see distant objects clearly; when the ciliary body contracts, The lens becomes thicker and its ability to deflect light becomes larger. Light from nearby objects converges on the retina, and the eyeball can see distant objects clearly.

Ask a question:

1. Due to physiological reasons, some people are no longer able to form images on the retina solely by adjusting their own eyes. How should this situation be dealt with?

2. Some people suffer from night blindness. What are the main nutritional deficiencies in their diet?

Myopia and its correction

Myopia occurs when the lens is too convex, causing light to focus in front of the retina.

Correction: Use a concave lens to first diverge the light, and then converge it on the retina through the lens.

Prescription of glasses

1. The reciprocal of the focal length of the lens is called the lens power (∮): ∮ = 1/f (the unit of f is m, the unit of ∮ is m-1)

2. The power of glasses is the power of the lens multiplied by 100: D= 100/ｆ

3. The power of convex lenses (lenses for farsightedness) is a positive number, and the power of concave lenses (lenses for myopia) is a negative number.

Example 1: Xiao Ming’s glasses are +200 degrees, his eyes are ______, the focal length of the lens is: ______m, it is ______ (convex lens or concave lens)

Example 2. Read the following passage and answer the questions:

The eyes of humans and some animals are very much like a camera. The lens in the eyeball is equivalent to a convex lens, and the retina is equivalent to an optical lens. When we look at objects, we adjust the curvature of the lens and change the curvature of the lens through the expansion and contraction of the ciliary body. The focal length enables objects of different distances to produce clear, inverted, reduced real images on the retina with the same image distance.

⑴What the human eye sees is a _____ image of _____. The difference between eyes and a camera is __________.

⑵The normal eye viewing distance is _____, and the optimal distance is _____.

Example 3: Xiao Ming’s and grandpa’s glasses are put together. Although grandpa’s glasses are reading glasses and Xiao Ming’s glasses are myopia glasses, the appearance of the two glasses is exactly the same. Please help Xiao Ming use the three simplest methods to distinguish between the two glasses. Glasses.

Answer: ⑴ Feel the shape: The one with a thick middle and thin edges is a far-sighted lens, and the one with a thin middle and thick edges is a myopia lens.

⑵ Look at the image: When you put it on a newspaper, the one that shrinks the virtual image is a myopia lens, and the one that enlarges the virtual image is a far-sighted lens.

⑶Look at the effect on light: those that converge light are far-sighted glasses, and those that diverge light are myopia glasses.

Operation:

1. Workbook: P70 pages for learning physics with hands and brain 2 and 4

2. Complete the life and supporting facilities in this section

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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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"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: 2024-06-09

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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