"Dispersion of Light" Light Phenomenon PPT Courseware 7

Description

"Dispersion of Light" Light Phenomenon PPT Courseware 7

Review and consolidate:

1.Law of reflection of light

2. The law of refraction of light

3. Characteristics of plane mirror imaging

4. The difference between real image and virtual image

1. Dispersion

The light from the sun illuminates the earth and makes all things shine. Before the 17th century, people always believed that white was the simplest color. It wasn't until 1666 that the British physicist Newton used a glass prism to disperse the sun, and this revealed the mystery of the color of light.

concept

After sunlight passes through a prism, it is decomposed into light of various colors. This phenomenon is called dispersion of light.

Sunlight (white light) is composed of red, orange, yellow, green, blue, indigo, and violet

It is a mixture of seven monochromatic lights.

Break down sunlight

Through this experiment, it can still be concluded that sunlight is a mixture of seven monochromatic lights: red, orange, yellow, green, blue, indigo, and violet.

2. Mixing of colors and lights

Red, green, and blue are called the three primary colors of light. Different colors can be mixed by using these three kinds of light.

Characteristics of infrared rays

1. Infrared rays can heat the irradiated objects and have a thermal effect. All objects are constantly radiating infrared rays outwards.

2. Infrared rays have strong ability to penetrate clouds and fog

The role of infrared rays

All objects in nature are constantly radiating infrared rays. The higher the temperature of the object, the stronger the infrared radiation it radiates.

The heat from the sun on the earth is mainly sent in the form of infrared rays.

Benefits of UV:

Appropriate exposure to ultraviolet rays helps the body synthesize vitamin D. Vitamin D can promote the body's absorption of calcium, which is beneficial to bone growth and many aspects of physical health.

Can kill microorganisms.

Sterilization with ultraviolet light (in hospital operating rooms, wards...)

It can make fluorescent substances glow and identify the authenticity of banknotes or trademarks.

Consolidation exercises

1. After sunlight passes through a prism, it will be decomposed into light of various colors. If a white screen is used to receive it, the order of colors on the white screen is red, _____, _____, ______, ______, ______, _____. this means________________.

2. The color of a color TV is produced by the electron gun in the TV shooting onto the phosphor on the inside of the screen. According to the mixing rules of color light, only three colors of electron guns, ______, ______, and _______, are needed in the TV. Can be matched with a variety of brilliant colors.

Exercise: 1. The color of a colored transparent object is determined by its _____, and the color of a colored opaque object is determined by its _____.

2. The color of an object that can absorb all colors of light is _____.

3. The color of an object that can reflect light of various colors is: ( )

A. White. B. Colorless.

C. Black. D. This color does not exist.

4. When a beam of light shines on a piece of paper and the paper appears red, then the relationship between this beam of light and the paper is: ( )

A. Red light, white paper B. White light, red paper

C. Red light, red paper D. The above situations are possible.

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Update Time: 2024-10-05

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

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