"Light and Color" PPT courseware

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"Light and Color" PPT courseware

Part 1: Learning about light sources

Can you define "light source"?

Light source: an object that is emitting light and emits its own light.

Common light sources include: the sun, fireflies, bonfires and torches, oil lamps, burning candles, glowing lamps, lasers, etc.

Because the moon, diamonds, eyes, mirrors, Halley's comet, etc. do not emit light by themselves, they are not sources of light.

Can you classify light sources?

Heat light source: sun, arc lamp, torch, etc.

Cold light source: fluorescent lamp, firefly

Light and Color PPT, Part 2: Classroom Experiment

Experiment: Explore the propagation route of light

1. Ask questions

2. Establish hypotheses

3. Design experimental plan

(1) Observe the path that the light emitted by the laser propagates in the air?

(2) Observe how the light emitted by the laser propagates in the water.

(3) Observe the path that the light emitted by the laser propagates through the glass?

4. Collect experimental evidence

Laser propagates in straight lines in air, water, and glass.

5 Conclusion:

Based on previous results, light propagates along straight lines in the same homogeneous material.

6. Communication and evaluation:

It was found that the propagation direction of light changes at the interface between air and water, air and glass. This is the refraction phenomenon of light that we will learn next.

Light and color PPT, the third part: the speed of light propagation

1. Fastest in vacuum: 3×108 m/s

2. Speed ​​in air: about 3×108 meters/second

3. The speed of light propagation: vacuum > air > water > glass

4. Light year: the distance traveled by light in one year.

1 light year = 9.46×1012 kilometers

Use scientific principles to solve life problems or life phenomena.

1. When there is thunder in life, why do we see the lightning first and then hear the thunder?

2. In a short-distance race, why does the timekeeper start the time when he sees smoke from the starting gun instead of when he hears the gunshot? If you listen to gunshots, will your grades get better or worse?

The speed of light in air is much greater than the speed of sound: 3×108 m/s>340 m/s.

Light and color PPT, part 4: exploration

How are circular spots formed in the shade of trees under sunlight?

1. Ask questions

What is the connection between the formation of light spots and the shape of light holes in leaves?

What is the connection between the formation of light spots and the size of light-transmitting holes in leaves?

2. Establish hypotheses

If the light-transmitting hole is circular, the shape of the light spot will be circular; if the light-transmitting hole is non-circular, the shape of the light spot will also be non-circular.

The smaller the light-transmitting hole is, the shape of the light spot will be circular; if the light-transmitting hole is too large, the shape of the light spot will be the shape of the hole.

3. Design experimental plan

Let the sun's rays pass through various holes of different shapes on the paper and observe the images of the spots formed.

Let the sunlight pass through various large holes of different shapes on the paper and observe the images of the spots formed.

4. Draw conclusions and explanations

The circular light spot is related to the size of the light hole, and the small hole can form the image of the sun.

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

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"Light and Color" PPT:

"Light and Color" PPT Part One Content: Introduction of New Lesson What objects in life can emit their own light? The sun, bonfires and torches, oil lamps, burning candles, electric lamps, lasers. Light sources: objects that can emit light by themselves. The moon and mirrors are also bright, they are light sources..

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Update Time: 2024-07-01

This template belongs to science courseware Zhejiang Education Edition Seventh Grade Science Volume 2 industry PPT template

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