"Eyes and Glasses" Lenses and their applications PPT download

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"Eyes and Glasses" Lenses and their applications PPT download

Part One Content: Basic Knowledge Key Points

Knowledge point 1 Eyes

1. The human eye is like a magical camera. The lens and cornea work together as the lens (convex lens) of the camera, and the retina is equivalent to the film in the camera. When people watch the scenery from far to near, the lens's ability to deflect light becomes stronger (optional "gets stronger", "weaker" or "unchanged"), and its thickness becomes larger (optional "gets bigger" " "get smaller" or "unchange").

2. With the development of science and technology, electronic products have been widely used, and the problem of myopia in teenagers has attracted social attention. They can see nearby objects clearly but cannot clearly see distant objects. The far point of a normal eye is at infinity, and the near point is about 10 cm.

Knowledge point 2: Myopia and its correction

3. (Lianyungang High School Entrance Examination) Myopia cannot see distant objects clearly because the image of the object falls in front of the retina (optional "front" or "back"), and you need to wear a concave lens (optional "convex lens" or "concave lens") ” ) to be corrected.

4. In the scenario shown in the figure, keep the positions of the candle and the convex lens unchanged, and move the light screen to the 80 cm scale line. No clear image will be obtained on the light screen. If the convex lens is viewed as a human eye, and the position of the light screen is regarded as the position of the retina, the imaging situation at this time is equivalent to the imaging situation when a myopic eye (optional "myopia" or "hyperopia") looks at an object.

Knowledge point 3: Hyperopia and its correction

5. As shown in the figure, the light from object point A passes through the lens of the eye and is imaged at point B behind the retina. To make the image closer to the retina, object point A should move to the left (optional "left" or "right"); To form an image on the retina, glasses made of suitable convex lenses should be worn.

6. After learning about lenses, classmate Li Hua went home and carefully studied his grandfather’s reading glasses and came to the following conclusion. Which of his conclusions do you think is incorrect (C)

A. Reading glasses can ignite white paper in the sun

B. Reading glasses can be used as magnifying glasses

C. Reading glasses are a concave lens

D. Grandpa is farsighted

Eyes and Glasses PPT, Part 2: Improvement of Comprehensive Ability

7. The imaging diagram of myopic eyes is as shown in the figure. Compared with eyes with normal vision, the lens of myopic eyes has a stronger ability to converge light (optional "convergence" or "divergence"); myopic eyes wear spectacle lenses. Its function is to diffuse the light so that it is imaged on the retina.

8. The classmates found that Wu Xiaofei’s reading posture was different from others. He always held the book far away, just like the elderly. Wu Xiaofei’s eyeballs are similar to picture B (please fill in “A” or “B”), and the shape of his new spectacle lenses is similar to picture A (please fill in “A” or “B”).

9. Due to some reason, Xiaoyun's eyesight is farsighted and myopic respectively. When she puts a 2B pencil 1 cm behind her glasses, she sees the shape of the pencil as shown in the picture through her glasses, then The lens on the right side of the picture is a convex lens (optional "convex lens" or "concave lens"), which corrects hyperopia (optional "myopia" or "hyperopia").

10. As long as the distance is appropriate, people can see both distant objects and nearby objects. The reason is (C)

A. Continuously change the image distance to form the image on the retina

B. Continuously change the object distance to form the image on the retina

C. Continuously change the convexity of the lens to form an image on the retina

D. None of the above statements are correct

11. A classmate looked out the window and then lowered his head to read a book. The shape of the lens (C)

A. unchanged B. thinned

C. Thickened D. Unable to determine

12. Which of the following statements about eyes and glasses is incorrect (D)

A. The human eye sees objects on the same principle as a convex lens.

B. One of the measures to prevent myopia is to keep the distance between the eyes and books at about 25 cm when reading and writing.

C. Myopia sees nearby objects clearly

D. The lens of hyperopia is thicker

13. Contact lenses are ultra-thin lenses that are directly attached to the surface of the cornea and can move with the movement of the eyeballs. The soft contact lenses currently used are made of formaldehyde hydroxyethyl acrylate (HEMA) and have a center thickness of only 0.05mm. Edge thickness of HEMA ultra-thin lenses worn by myopia patients (C)

A. Less than 0.05 mm B. Equal to 0.05 mm

C. Greater than 0.05 mm D. Can be any value

14. The lenses with different thicknesses shown in Figure 1 are all made of the same glass material. In order to illustrate the characteristics of the lens when normal eyes see distant and near objects, Xiao Ming conducted the experiment in Figure 2. First, he took lens B and placed it on the light bench. The flame of the candle lit at point A formed an inverted and reduced image on the light screen. Then, Move the candle to B and C respectively, replace lens B with different lenses, but the positions of the lens and the light screen remain unchanged, and different degrees of inverted and reduced images are formed on the light screen, (B)

A. When the candle moves to B, replace B with C

B. When the candle moves to B, replace B with A

C. When the candle moves to C, replace B with A

D. When the candle moves to C, replace B with D

Eyes and Glasses PPT, Part 3: Expanding Research and Breakthroughs

17. 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/?. The power usually referred to is the value of the lens power multiplied by 100. Xiaoya’s myopia is 500 degrees. Please calculate the power and focal length of the spectacle lenses Xiaoya wears.

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Update Time: 2024-07-23

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