"The Secret of the Rainbow" PPT

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"The Secret of the Rainbow" PPT

Part One: The Rainbow Appears

When the rainbow appears

After the rain, by the fountain, by the water, by the waterfall

What factors may be related to the appearance of rainbows?

sunshine, water drops

Let’s do a simulation experiment below

Experimental requirements:

For each group of 10 people, choose one person to spray, one person will record the experiment, and the others will watch the relationship between the size of the water droplets and the formation of the rainbow.

Kind tips:

1. The team leader shall do a good job in the division of labor in the experiment;

2. Do not spray the sprayer at people;

3. Spray with your back to the sun, and pay attention to the wind direction to prevent the mist from being blown by the wind;

4. When spraying, everyone in the group should go behind the demonstrator and choose a suitable angle to watch, so as not to wet their clothes.

A prism can decompose sunlight into seven colors of light: red, orange, yellow, green, blue, indigo, and violet.

Place the plane mirror in the basin and adjust the plane mirror until the light is reflected to the ceiling in front of the entrance hall, and a rainbow can be seen.

A plane mirror and water form a prism.

I see:

The small water droplets suspended in the air act as prisms, breaking down the sunlight to form a beautiful rainbow.

The Secret of the Rainbow PPT, Part 2: The Formation of the Rainbow

How is a rainbow formed?

Sunlight is composed of seven colors of light. After the rain, there are many small water droplets in the air. Sunlight shines on small water droplets, which break down the sunlight into seven colors of light, forming a rainbow.

Life and Application

"How can you see a rainbow without going through wind and rain?" The staff of Linyi Yishui Rainbow Valley artificially created rainbows based on the causes of rainbows, so that tourists can see rainbows every day and enjoy auspicious rain every day, which has brought considerable economic income to local residents. .

Why is the rainbow curved?

Reason one: related to the wavelength of light

The wavelength of light determines how much light is bent. Originally, light travels in a straight line. Once it enters the water, it is refracted. All the small water droplets in the sky are arranged in a circle. When the relative positions of the water droplets on the circle, the sun, and the human eye are the same, the colored light refracted from the water droplets can be projected into the human eye. The degree to which light bends as it passes through a water droplet depends on the wavelength (i.e., color) of the light—red light bends the most, followed by orange and yellow light, and so on, with violet light bending the least. So each color appears in a different location in the sky.

Reason 2: It has a lot to do with the shape of the earth

Because the Earth's surface is a curved surface and is covered by a thick atmosphere, the water content in the air after a rain is higher than usual, causing refraction when sunlight strikes small water droplets in the air. At the same time, because the atmosphere on the earth's surface is an arc, sunlight is refracted on the surface to form the arc-shaped rainbow we see.

The Secret of the Rainbow PPT, Part 3: After-class Improvement

The natural world is mysterious and unpredictable, and there are still many unknown secrets waiting for us to discover and explore. I hope you will observe more and think more, use weekends, holidays, etc. to boldly explore natural phenomena, and keep records, and return to school to talk to your teacher Share and communicate with classmates. There will be scientists in our class who are as accomplished as Darwin and Newton.

Why did the people and horses disappear before they crossed the bridge? "

Rainbows generally do not appear in the sky for a long time and gradually disappear after a while. This is because the small water droplets in the sky gradually evaporate due to heat.

The Secret of the Rainbow PPT, Part 4: Practice

1. Sunlight is not a monochromatic light, it is composed of ( ) colored light.

2. Use ( ) to decompose sunlight into seven different colors of light.

3. The colors of the rainbow from outside to inside are ( ), ( ), ( ), ( ), ( ), ( ), ( ).

5. Among the seven colors of light, "indigo" refers to ( ).

6. The formation of rainbow is inseparable from ______ and _______.

7. The formation of rainbows has nothing to do with water. ( )

8. You can also see a rainbow in front of the fountain. ( )

9. Place the prism under the sun and adjust the angle to see seven colors of light. ( )

10. The order of rainbow colors is fixed. ( )

11. The innermost color of the rainbow is purple. ( )

12. Turn your back to the sun to create a rainbow. ( )

Keywords: Qingdao edition fourth grade science PPT courseware for the second volume free download, The Secret of the Rainbow PPT download, .PPT format;

For more information about the "Secret of the Rainbow" PPT courseware, please click the "Secret of the Rainbow" PPT tab.

"The Secret of the Rainbow" PPT courseware:

"The Secret of the Rainbow" PPT courseware Part 1: Teaching objectives: By understanding the causes of rainbows, students will know that sunlight is composed of seven different colors of light. Cultivate students' reasoning abilities (inferring the cause of rainbows based on dispersion experiments), and experimental abilities (..

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Update Time: 2024-06-25

This template belongs to science courseware Qingdao Edition Fourth Grade Science Volume 2 industry PPT template

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