On December 17, Zhang Chaoyang, founder, chairman of the board of directors and CEO of Sohu, explained the "Stepan's Law" in physics to the audience in the Sohu video broadcast room. It is understood that the Stefan-Boltzmann law, also known as Stefan-Boltzmann law, is a famous law in thermodynamics, which is: the total energy radiated by a unit area of a black body surface in unit time (called the radiance or energy flux density of the object) j* is proportional to the quaternion of the thermodynamic temperature T (also known as absolute temperature) of the black body itself.
Zhang Chaoyang said, "The total energy radiated by a blackbody surface per unit area per unit time is proportional to the quadrangle of the thermodynamic temperature of the blackbody itself." As early as 1879 and 1884, Stefan and Boltzmann obtained this law from experimental and theoretical aspects, respectively. "Today, it's a simple corollary of the relatively complex blackbody radiation formula."
In addition, Zhang Chaoyang also calculated the surface temperature of the sun in the live broadcast. When sunlight reaches the earth, what is the intensity of sunlight that humans feel? According to Stefan's law, Zhang Chaoyang calculated that it can receive about 1400 watts of thermal radiation power per square meter. "When sunlight reaches the Earth, the intensity of the light has weakened a lot because of the divergence of the angle, and it is inversely proportional to the square of the distance." "If you take a detector to measure the absorption intensity of light, combined with some other parameters, you can also estimate the ratio of the sun to the earth's radius in reverse," he said. ”
There is also the heat loss of the human body, Zhang Chaoyang explained why the human body loses temperature, reminding netizens to always pay attention to heat preservation. There are two ways of human heat dissipation, one is the radiation mode, and the other is that there is a certain degree of heat exchange between the human body and the surrounding air molecules. Human body temperature loss is mainly due to infrared radiation, for example, when the ambient temperature is 20 degrees, the human body temperature is 36 degrees, the human body radiates outward with a body temperature of 36 degrees, and at the same time absorbs 20 degrees of ambient temperature radiation, such a temperature difference produces an energy difference, and the human body loses energy.
The greenhouse effect is because "there is too much carbon dioxide and water vapor in the atmosphere, so that the light absorbed by the earth cannot be fully radiated out, and about 10% is trapped on the earth." "The Earth's temperature is basically constant because the light absorbed and the light radiated out can create a balance." "And a lot of carbon dioxide upsets that balance."
By explaining Stepan's law, Zhang Chaoyang also led the topic to topics such as the greenhouse effect and reducing carbon emissions. It is understood that at present, "Zhang Chaoyang's Physics Class" has been live broadcast for more than ten issues, which is the main knowledge video strategy of Sohu Video, and more knowledge bloggers will be invited to settle in the future.