"Lens in Life" Lens and its Application PPT Teaching Courseware

"Lens in Life" Lens and its Application PPT Teaching Courseware

The first part: sorting out new knowledge

1 camera

1. The principle of the camera: As shown in Figure 5-2-1, the lens of the camera is equivalent to a ________ mirror, and the film of the camera is equivalent to ________.

2. Imaging characteristics: When the camera is working, the distance from the photographed object to the convex lens is relatively ________, and the distance from the film to the convex lens is relatively ________, so the image obtained on the film is _____________.

2. Projector

1. Principle of projector: As shown in Figure 5-2-2, the lens of the projector is equivalent to a ________ mirror, and _______ is equivalent to the object; the function of the plane mirror is _______________, so that the light energy directed to the ceiling is Image on the screen.

2. Imaging characteristics: When the projector is working, the distance from the projection film to the lens is ______, far ______ (optional "greater than" or "less than") the distance from the screen to the projector, what is obtained on the screen is ____________ like.

Three magnifying glasses

1. A magnifying glass is a ________ with a short focal length.

2. Imaging characteristics: Place the magnifying glass at an appropriate position above the object, and a ____________ image can be formed through the magnifying glass. At this time, the image and the object are on the ______ side of the convex lens.

[Expand] Ensure that the magnifying glass forms an upright, enlarged image. Move the magnifying glass and find that: the closer the magnifying glass is to the object, the smaller the image formed; the farther the magnifying glass is from the object, the larger the image formed.

Lens PPT in life, part 2: application examples

Type 1: Principles and Applications of Cameras

Example 1: Figure 5-2-4 shows the imaging diagram of the camera. The correct one of the following statements is ()

A． The camera lens is a convex lens

B. The image formed by the camera is an upright and reduced image

C. To make the image on the film larger, just extend the lens forward

D. To produce a reduced image on film, the object must be closer to the lens

[Rule Summary]When taking pictures with a camera, if no one or scenery enters the lens, it means that the image is too large. If all the people or more scenery enter the lens, the image needs to be smaller, and the camera should be moved away. People or scenery, while the camera zooms back a little.

Type 2: Principles and applications of projectors

Example 2 As shown in Figure 5-2-5, in the practical activity of "Practice Adjusting the Projector", Xiao Ming made adjustments to make a clear picture appear on the screen, but the picture exceeded the screen range. To this end, Xiao Ming’s operation should be: appropriately ________ (optional “increase” or “decrease”) the distance between the projector and the screen, and adjust the convex lens

Move to ________ (optional "up" or "down") as appropriate.

[Analysis]The picture exceeds the screen range, indicating that the image is too large. The distance between the projector and the screen should be appropriately reduced (reduce the image distance), and the convex lens should be moved upward appropriately (increase the object distance).

[ Summary of rules] When using a projector: ① The distance from the projection film to the lens (object distance) is smaller than the distance from the lens to the screen (image distance). ②The closer the slide is to the lens, the larger the image on the screen will be, and the greater the distance from the image to the lens will be. ③The slide film and its image are on both sides of the lens. ④The projection film forms an inverted and enlarged real image on the screen.

Type 3: Principle and application of magnifying glass

Example 3: When looking at fingerprints with a small military magnifying glass, I feel that the fingerprint image is too small. To make the fingerprint image larger, the correct approach is ()

A． Keep your eyes and fingers still and bring the magnifying glass close to your fingers

B. Keep your eyes and fingers still and keep the magnifying glass away from your fingers

C. Keep the magnifying glass and your fingers still and keep your eyes close to the magnifying glass

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

[Analysis]The magnifying glass is made based on the principle of a convex lens standing upright and amplifying a virtual image. The imaging rule is that the farther the object is from the convex lens (closer to the point), the larger the image will be. To make the fingerprint image larger, the magnifying glass should be kept away from the finger.

[Rule Summary] If you move the convex lens as far away from the object as possible, but the object is still within the focal length of the convex lens, you can magnify the small object larger.

Type 4: Real image and virtual image

Example 4 2018·Hechi Among the four scenarios shown in Figure 5-2-6, the real image is ()

[ Analysis is a real image, so B is consistent with the meaning of the question; the fish in the water seen by the people on the boat is a virtual image of the fish formed by the refraction of light, so C is not consistent with the meaning of the question; what is seen through the magnifying glass is upright, magnified A virtual image, so D does not meet the meaning of the question.

[Method guidance]Methods for judging real and virtual images

Use a light screen to accept images. What can be presented on the light screen is a real image, and what cannot be presented on the light screen is a virtual image. In reflection imaging, the real image and the object are on the same side of the mirror, and the virtual image and the object are on different sides of the mirror; in refraction imaging, the real image and the object are on different sides of the lens, and the virtual image and the object are on the same side of the lens.

Lenses in Life PPT, Part 3: Class Feedback

1. Which of the following items does not apply the principle of convex lens imaging ()

A． Full-length mirror B. projector

C. cameraD. magnifier

2. Figure 19-1 shows the imaging diagram of the camera. The correct one of the following statements is ()

A． The camera lens is equivalent to a convex lens

B. The camera lens is equivalent to a concave lens

C. The image formed is an upright, reduced real image

D. The resulting image is an inverted, reduced virtual image

3． Figure 19-2 shows the schematic diagram of projector imaging. Which of the following statements is wrong ( )

A． The projector lens is equivalent to a convex lens

B. The object is relatively close to the projector lens, such as magnified or inverted

C. The image produced by the projector is a real image

D. The properties of the image produced by the projector are exactly the same as those of a magnifying glass

4. As shown in Figure 19-3, when ginseng is soaked in wine, what you see through the wine bottle is an enlarged virtual image of ginseng. At this time, the bottle and wine are equivalent to one ()

A． Convex lens B. concave lens

C. Convex mirror D. concave mirror

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