The COVID-19 has swept the world this year. Except for masks, most people are most familiar with their body temperature. Why can infrared thermometers measure body temperature? Today we will use light and circuits in junior high school physics to explore and learn the principles.
Let’s talk about light first. 1. In addition to visible light (red, orange, red, green, blue, blue and purple), there is also invisible light (infrared and ultraviolet). 2. The wavelength and frequency of light are inversely proportional, that is, different lights correspond to different frequencies and wavelengths. 3. The human body continuously radiates infrared rays, and the higher the temperature, the stronger the infrared rays.
Next we talk about the circuit.
1. The weak current change in the circuit can be displayed by an ammeter.
2. The resistance increases as the temperature increases, but it is not easy to show a slight change, so thermistor can be used, which is very sensitive to heat.
Combining light and electricity, the infrared rays of the human body can be received, and the changes in the intensity of the infrared rays can cause changes in resistance, thereby causing current changes, and current changes can correspond to the corresponding temperature. This is the general working principle of the infrared electronic clinical thermometer.
The content of junior high school physics can solve a lot of things in life. Junior high school physics students can learn more with the reality of life, which will get twice the result with half the effort.