"Invisible Light" Light Phenomenon PPT Courseware

Description

"Invisible Light" Light Phenomenon PPT Courseware

learning target:

1. What is spectrum?

2. What is infrared? What are its applications?

3. What is ultraviolet light? What are its applications and what are its disadvantages?

1. Spectrum

The seven different colors of light that are decomposed into sunlight are arranged in the order of red, orange, yellow, green, blue, indigo, and violet to form a spectrum.

Module one infrared

In the part of the spectrum other than the red light, the thermometer reading will also increase, indicating that there is also energy radiation here, but it is invisible to the human eye. This radiation is called infrared.

Let the sunlight pass through the prism and redo the dispersion experiment. Place the thermometer glass bulb in three different positions except red light, visible light, and purple light, and observe the changes in the thermometer's indication.

1. Discovery of infrared rays

In 1800, when the scientist Herschel was observing the temperature of various regions in the dispersion spectrum of sunlight, he discovered that the distribution of thermal effects was very uneven. There is also a thermal effect measured outside the red light, and it is more obvious than other parts.

Scientists call this invisible "light" infrared.

2. Characteristics of infrared rays:

1. Strong thermal effect - thermal effect.

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

2. The ability to penetrate clouds and fog is relatively strong.

Infrared rays have strong ability to penetrate clouds and fog, and are used for long-distance, high-altitude, and night photography, and remote sensing technology (exploring the earth, finding water sources, monitoring forest fires, estimating the growth and harvest of large-area crops, predicting storms and cold waves, etc.)

3. Application of infrared rays

1. Thermal effect - infrared imaging

If you use this infrared camera to shoot at the host, what phenomena can you see?

The host's forehead is very red, indicating a high temperature;

The surface of the clothes is blue, indicating that the temperature is low;

The female presenter's hands are black, indicating that her hands are cooler.

1. The concept of ultraviolet light

Invisible light beyond violet on the spectrum is called ultraviolet light.

Ultraviolet rays have strong chemical effects.

Ultraviolet light can make fluorescent substances glow - fluorescence effect

2. Ultraviolet characteristics:

1. Enable fluorescent substances to emit light

2. Kill microorganisms

3. Helps the body synthesize vitamin D

3. Application of ultraviolet light

1. Fluorescence effect----UV currency detector

2. Kill microorganisms----Ultraviolet sterilization lamp

3. Helps the body synthesize vitamin D

4. Harm----skin cancer

Compliance testing

1. A prism can decompose sunlight into ____ different colors of light. Arranging them in order is _______________.

2. Infrared ray is an invisible light. The temperature of an object can be _____ by the irradiation of infrared ray. Any object can radiate infrared rays, and the infrared rays emitted by objects with higher temperature also _______.

3. Ultraviolet rays are also an invisible light. Ultraviolet rays can kill _______ and make fluorescent substances ____. Appropriate ultraviolet rays can help _____________. Excessive ultraviolet rays can cause _______ to the human body.

4. In the recent U.S. and British coalition operations against Iraq, U.S. and British soldiers wore infrared night vision goggles at night to detect the enemy even in the dark night. Infrared night vision goggles are made based on the principle that the ______ of people at night is _____ than the temperature of surrounding vegetation or buildings, and the ______ of human body radiation is greater than their ______.

Keywords: light phenomenon teaching courseware, invisible light teaching courseware, Lujiao version eighth grade physics PPT courseware download, eighth grade physics slide courseware download, light phenomenon PPT courseware download, invisible light PPT courseware download, .PPT Format;

For more information about the "Light Phenomenon Invisible Light" PPT courseware, please click on the "Light Phenomenon Invisible Light ppt" tab.

File Info

Update Time: 2024-09-15

This template belongs to Physics courseware Lu Jiao edition eighth grade physics volume 1 industry PPT template

Preview