"Dispersion of Light" Light Phenomenon PPT Download

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"Dispersion of Light" Light Phenomenon PPT Download

The first part: sorting out new knowledge

1. Dispersion

Dispersion of light: The phenomenon in which sunlight is decomposed into seven colors of light after passing through a prism. Rainbows are formed when sunlight is refracted by small water droplets in the air as it travels.

[Pointing] (1) The dispersion phenomenon of light shows that sunlight (white light) is not monochromatic light, but a complex color light composed of various monochromatic lights. As shown in Figure 4-5-1, the reason for the phenomenon of light dispersion is that light of different colors has different degrees of deflection when refracted by a prism. Red light has the smallest degree of deflection, and violet light has the largest degree of deflection.

(2) The decomposed colored light can also be combined into white light.

Mixing of two colors of light

The three primary colors of light: ______, ______, ______. By mixing the three primary colors of light in various proportions, various colors of light can be obtained. The rich colors on the color TV screen are produced by mixing the three primary colors of light in different proportions.

Three Invisible Light

1.Spectrum

A prism can decompose sunlight into several different colors of light, which are arranged in a certain order to form the visible spectrum of the sun.

2.Infrared ray

(1) Definition: Beyond ______ in the spectrum, there is an invisible light called infrared.

(2) All objects are constantly radiating infrared rays. The higher the temperature of the object, the more ______ the infrared rays radiated.

(3) Characteristics of infrared rays

① The thermal effect is strong. Infrared rays can increase the temperature of the object being irradiated, so people use infrared rays to heat objects.

② It has strong ability to penetrate clouds and fog. Taking advantage of this characteristic, people invented __________ technology.

③ Infrared rays can also be used for remote control. For example, when different keys on the TV remote control are pressed, different infrared ray pulses can be emitted to achieve remote control.

3.Ultraviolet rays

(1) Definition: Beyond ______ in the spectrum, there is an invisible light called ultraviolet light.

[Explanation]Ultraviolet rays themselves are invisible. The UV lamp looks light blue because in addition to ultraviolet rays, it also emits blue light and violet light.

(2) Characteristics of ultraviolet light

① It has strong physiological effects and can kill ________. Appropriate ultraviolet rays help the human body synthesize _______. Excessive ultraviolet rays are very harmful to the human body.

② It has a strong chemical effect and can make the film ________, apply the fluorescence effect of ultraviolet light, and can also carry out ________, such as using ________ to make a mark on the RMB, which can be identified under ultraviolet light, etc.

Dispersion of light PPT, part 2: application examples

Type 1 Dispersion of light

Example 1 At noon on April 9, 2018, a beautiful halo appeared over Kunming. As shown in Figure 4-5-2, a huge colorful halo surrounded the sun, which was extremely gorgeous and amazing. At an altitude of 5000 meters, water vapor forms small ice crystals when it is cooled. After the sunlight hits the small ice crystals, they are decomposed into seven colors of light: red, orange, yellow, green, blue, indigo, and violet. In this way, a circle appears around the sun. Huge rings of color called "halos." Which of the following statements is correct ()

A. The formation of small ice crystals when water vapor is cooled is a solidification phenomenon.

B. Water vapor needs to absorb heat to form small ice crystals when it is cooled

C. Sunlight irradiates small ice crystals and decomposes into seven colors of light through reflection

D. The small ice crystals decomposed into seven colors of light after being irradiated by sunlight are the dispersion phenomenon of light.

[ Analysis Light, C is wrong; sunlight decomposes into seven colors of light after irradiating small ice crystals, which is the dispersion phenomenon of light, D is correct.

Example 2 The phenomenon shown in Figure 4-5-4 is related to the dispersion of light ()

Type 2: Mixing of colored lights

Example 3: The most eye-catching thing at the Shanghai World Expo is the crystal clear, trumpet-shaped building-"Sunshine Valley", as shown in Figure 4-5-5. The LED starlights arranged on the Sunshine Valley nodes and the solar LED starlights arranged on the top can emit three colors of light at night: _______, _______, and _______. They can be matched in proportion to achieve various color changes, achieving "unpredictable changes" , Ambilight” effect.

Type 3 invisible light

Example 4 Which of the following statements about infrared rays is incorrect ()

A． "Thermograms" taken with infrared rays help diagnose diseases

B. Install a night vision device on the rifle's sight to capture the enemy at night

C. In hospital operating rooms and wards, you can often see the use of infrared lights for sterilization

D. Infrared rays can be used to control instruments and equipment remotely

Dispersion of light PPT, Part 3: Class feedback

1. Among the phenomena shown in Figure 17-1, the dispersion phenomenon of light is ( )

2. Which of the following statements about infrared and ultraviolet rays is correct ( )

A． Infrared rays can be used to identify the authenticity of banknotes

B. Ultraviolet light can be used on the sight of a rifle to make a night vision device, which can capture the enemy at night

C. In hospital operating rooms and wards, you can often see the use of infrared lights for sterilization

D. Infrared rays can be used to control instruments and equipment remotely

3． In 1666, the British physicist Newton used glass to disperse sunlight and revealed the mystery of the color of light. It was discovered that sunlight is broken down into a band of colored light, the colors of which are __________________. This shows that white light is a mixture of various colors of light.

4. The speed of sunlight in vacuum is ________m/s. The phenomenon that sunlight is decomposed into seven colors of light after passing through a prism is called _________ of light.

5. People call the three colors of red, _______, and _______ the three primary colors of color light. As shown in Figure 17-2, these three colors of light are mixed in a certain proportion (shaded part) to form ________.

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"Dispersion of Light" Light Phenomenon PPT Teaching Courseware Part One Content: Knowledge Points Basic Knowledge Point 1 Dispersion of Light 1. Let a beam of sunlight pass through a prism to obtain various colored lights. This is the dispersion phenomenon of light; from this we can know that sunlight Is it complex color light (optional monochromatic light or complex...

"Dispersion of Light" Light Phenomenon PPT:

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Update Time: 2024-10-14

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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