"Magnifying Glass" Micro World PPT Courseware

Description

"Magnifying Glass" Micro World PPT Courseware

scientific concept

A magnifying glass is a convex lens. The convex lens has the function of magnifying the image of an object. You can see more details when observing an object with a magnifying glass.

Magnifying glass lenses are characterized by being clear and thick (convex) in the middle. Magnifying glasses are widely used in many aspects of people's life and production.

The function of magnifying glass——

Magnified image of an object - the object does not become larger

Condensation effect - Concentrating sunlight to ignite matches or paper

New discoveries under a magnifying glass (use a magnifying glass to carefully observe a small area of ​​pictures, screens, fabrics, etc.)

Image --- consists of color dots. Divide the image into many dots (color-by-color printing is impossible!) Negative copy

The monitor screen is composed of color dots (red, green and blue)

Use a magnifying glass to observe the photos on the printed matter and the screens of televisions and computers. The result of observation is that not only the image is enlarged, but also a secret that cannot be discovered by the naked eye is discovered, that is, the image is composed of color points.

Why are photos in print made of dots?

Because printing uses dot technology. Color drawings or color photos have thousands of colors on the screen. It is almost impossible to print thousands of colors one by one. When printing, the original manuscript is first color decomposed into four color plates of cyan, magenta, yellow, and black, and then screened. Once the original image is screened, the image is divided into countless regularly arranged dots to form a dot negative, and finally copied and dried into various colored printing plates. Color synthesis is performed during printing. Since the resolution ability of our eyes has certain limitations, we cannot distinguish it.

When you use a magnifying glass to observe TV and computer screens, why do you see small dots composed of red, green, and blue colors?

This is because after the lens of the TV camera takes in the image of a person or scene, it uses a refractor to divide the light into three channels. The three camera tubes respectively detect the three primary colors of red, green, and blue in the light, and then transform the perceived light. for electrical signals. After being received by the color television, these electrical signals control the three electron beams (electron guns) in the color picture tube. The inner wall of the bottom of the picture tube is coated with a layer of photosensitive material - phosphor, forming a fluorescent screen. The fluorescent screen contains 400,000 groups of fluorescent dots on the outward side, each group consisting of three fluorescent dots. They produce corresponding red, green, and blue light after being excited by the electron beam. These fluorescent dots are very small and cannot be seen with the naked eye, but with a magnifying glass you can see that they are composed of red, green, and blue colors.

What does magnification relate to?

The greater the protrusion of the magnifying glass, the greater the magnification factor. It can be inferred that the transparent object will have the largest magnification factor.

The greater the protrusion of the magnifying glass, the greater the magnification. It can be inferred that spherical transparent objects have the greatest magnification.

The use and history of magnifying glasses

Lighting paper under sunlight is its ____ function; observing the tiny world is its ____ function.

People invented the magnifying glass as early as ____ years ago.

Require:

1. Observe the chopsticks in the water from the side and front

2. When observing, find the correct observation point and location.

3. After the observation, share your conclusions with the group.

Generally, we call lenses that are thick in the middle and thin at the edges called convex lenses.

(Because the convex lens has the function of magnifying, people often call it a magnifying glass in life)

Lenses that are thin in the middle and thick at the edges are called concave lenses

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For more information about the "Tiny World Magnifying Glass" PPT courseware, please click the Tiny World PPT Magnifying Glass PPT tab.

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Update Time: 2024-06-26

This template belongs to science courseware Science Edition for Sixth Grade Science Volume 2 industry PPT template

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