"End of Chapter Summary and Improvement" Lens and its Application PPT

"End of Chapter Summary and Improvement" Lens and its Application PPT

Part One: Key Breakthroughs

Type 1 Comparison of convex lenses and concave lenses

1. The following four pictures are the optical path diagrams of light passing through the lens. The correct one is (B)

2. According to the incident light and exit light as shown in the figure, the optical element that should be filled in the dotted box is (A)

A. Convex lens B. Concave lens

C.Plane mirror D.Concave mirror

3. As shown in the figure, a convex lens is placed in front of a plane mirror. When observing the mirror with your eyes, the light beam seems to diverge from M, then the focal length of the convex lens is (D)

A.0.4 m B.0.3 m C.0.2 m D.0.1 m

4. The optical path of a beam of parallel light passing through a certain lens is as shown in the figure. It can be seen that the following statement is correct (C)

A. The lens is a convex lens

B. The lens can have real focus

C. Lenses made of this type of lens can correct myopia

D. Lenses made of this type of lens can correct farsightedness

5. As shown in the figure, a beam of light enters the optical instrument at O ​​and then converges at point S on the main optical axis. After the optical element is removed, the light converges at point S', then the mirror must be (D)

A. Convex mirror B. Plane mirror

C. concave lens D. convex lens

Type 2: Application of lenses in daily life

6. (Tongliao High School Entrance Examination) Recently, a "selfie artifact" has become popular, which brings convenience to travelers. As shown in the picture, compared with taking a selfie directly with a mobile phone, you can use a selfie stick (B)

A.Increase the image distance

B. Increase the viewing range

C. Increase the size of the portrait

D. Shorten the distance from the scene to the lens

7. As shown in the picture, the old woman is reading a book with a magnifying glass. In order to see a larger and clearer image, she should (A)

A. Keep the book and eyes still, and keep the magnifying glass farther away from the book

B. Keep the book and eyes still, and keep the magnifying glass closer to the book

C. Keep the book and magnifying glass still, and keep your eyes closer to the book

D. Keep the book and magnifying glass still, and keep your eyes away from the book

8. Which of the following statements about microscopes and telescopes is correct (A)

A. Use a microscope to observe an object. What you see is a virtual image of the object after it has been magnified twice.

B. What you see through a telescope is the real image of an object after it has been magnified twice.

C. The objective lenses of all telescopes are equivalent to convex lenses

D. None of the above statements are correct

End-of-Chapter Summary and Improvement PPT, Part 2: Experimental Activities

Experiment: Explore the rules of imaging by convex lenses

1. Experimental equipment: light bench, convex lens, light screen, candle.

2. Experimental device: as shown in the figure.

3. Experimental operation

(1) Understand the focal length of the convex lens, or use the parallel light focusing method to measure the focal length.

(2) Light the candle and adjust the height of the convex lens and light screen so that their centers are at the same height as the center of the candle flame.

(3) During the experiment, the position of the convex lens does not change. By changing the position of the candle (adjusting the object distance), moving the light screen to find the image, note down the object distance, image distance, characteristics of the image each time and the image of the object during the movement. Changes.

(4) If no image can be found on the light screen in a certain experiment, it may be that the distance between the candle and the lens is less than one focal length or the candle is exactly at one focal length.

(5) When observing a virtual image, the human eye should look through the convex lens on the other side of the lens.

4. Precautions

When forming a real image, pay attention to moving the light screen back and forth until you find the clearest image.

5.Experimental conclusion

(1) When u>2f, it becomes an inverted and reduced real image.

(2) When u=2f, it becomes an inverted, equal-sized real image.

(3) When f

(4) When u=f, there is no image.

(5) When u

End-of-Chapter Summary and Improvement PPT, Part Three: Connection between Junior High School and High School

The relationship between object distance, image distance and focal length in the imaging law of convex lenses: In the experiment of the imaging law of convex lenses, u represents the object distance, v represents the image distance, and f represents the focal length. When the convex lens forms a real image, it satisfies 1/u+1/v=1/f. If the distance between the object images is L, then L≥4f.

[For training]

1. In the experiment on the imaging law of convex lenses, u represents the object distance, v represents the image distance, and f represents the focal length. When it becomes a real image, it satisfies 1/u+1/v=1/f. The object distance was measured in a certain experiment. is 30 cm and the image distance is 15 cm, then the focal length of this convex lens is 10 cm.

2. As shown in the figure, object AB can form an equally large and inverted real image on the other side of the convex lens. The object distance u=OB, the image distance v=OD, and the focal length of the convex lens is f. The relationship between object distance, image distance and focal length is 1/f=1/u+1/v.

(1) Please combine your mathematical knowledge to prove that the condition for a convex lens to form a real image of equal size is u=2f;

(2) In physics, the ratio of image distance to object distance is used to express the magnification of a convex lens, that is, m=v/u. Please combine the formula with the relationship between u and v when the projector is imaging, and explain the magnification of the projector when imaging. Is the rate m greater than 1 or less than 1?

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