"Lens and Vision" PPT courseware

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"Lens and Vision" PPT courseware

Part 1: Think about it

1. Have you ever encountered or used lenses in your life?

Myopia glasses, magnifying glass, telescope-------

2. What are the common characteristics of different lenses?

The materials (glass, resin, crystal, etc.) vary, but the characteristics are the same: Transparency - allows light to pass through.

3. What is the difference between magnifying glasses and myopia lenses?

A magnifying glass is thick in the center and thin at the edges;

Myopia glasses are thin in the center and thick at the edges.

Lenses and Vision PPT, Part 2: Lenses

1.Types of lenses

Thick in the center, thin at the edges Convex lens

Thin in the center, thick at the edges Concave lens

Activity 2: The effects of different lenses on light

Use a light source to shine on the convex lens, hold a piece of white paper on the other side of it, and move the convex lens or paper back and forth until the light spot on the paper becomes the smallest and brightest.

If we use a concave lens and do the above experiment again, can we still get the smallest and brightest light spot on the paper?

Three special rays of convex lens

(1) The light rays parallel to the main optical axis will be converged at the focus after being refracted by the convex lens.

(2) After the light passing through the focus is refracted by the convex lens, the refracted light will be parallel to the main optical axis.

(3) The propagation direction of light passing through the optical center does not change.

2. The effect of concave lens on light divergence

Given a lens, what methods can you use to determine whether it is a convex lens or a concave lens?

Touch: Touch the lens directly with your hands. The one with a thick middle and thin edges is a convex lens. If you find that the one with a thin middle and thick edges is a concave lens.

Look: put the lens close to the book and observe the size of the font through the lens. If the font becomes larger, it is a convex lens, and if it becomes smaller, it is a concave lens.

Photo: Use a flashlight to shine on a lens. A convex lens is a lens that converges light, and a concave lens is a concave lens that diverges light.

Lens and Vision PPT, Part 3: Class Summary:

convex lens

Shape: Lens with thick center and thin edge

Function: Converging light

concave lens

Shape: Lens with thin center and thick edges

Function: has a divergent effect on light

Keywords: Zhejiang Education Edition seventh grade science PPT courseware for the second volume free download, lens and vision PPT download, .PPT format;

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"Lens and Vision" PPT download:

"Lens and Vision" PPT Download Part One: Pre-class Thoughts 1. How to roughly measure the focal length of a convex lens? Face the convex lens to the sun, use a piece of white paper as a light screen on the other side of the convex lens, so that the convergence point of the light appears on the light screen, and use a scale to measure...

"Lens and Vision" PPT:

"Lens and Vision" PPT Part One Content: Lenses in Life Observe the following lenses and talk about the characteristics of these lenses Thick in the middle Lenses with thin edges Convex lenses Thin in the middle Lenses with thick edges Concave lenses... ... Lens and vision PPT, second...

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Update Time: 2024-11-22

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