It can be inferred from the experimental results of Zhang Hua in Li Minghe that the sunlight reflected by each glass plate is only half of the incident light energy, that is to say, half of the sunlight incident on the glass plate is reflected by the glass plate. Therefore, the solar energy transmitted through the glass plate accounts for 50% of the solar energy radiated to the glass plate.
(2) Experimental scheme: If the sunlight is always incident vertically during the experiment and the inside of the drying tank is painted black, it can be considered that the sunlight injected into the drying tank is no longer reflected, and the heat absorption efficiency of the drying tank is 50%. In addition, there is an insulation layer around the drying tank, which can be considered as no heat loss. If the heat absorbed by the drying tank is completely used to raise the temperature of water, how much can the energy of a certain quality of water in the incubator increase in a certain period of time? By measuring the area where sunlight vertically irradiates the surface of the object, we can calculate the energy of sunlight irradiating the surface of the earth in unit time and unit area when sunlight vertically irradiates the surface of the earth.
The experimental steps are as follows:
(1) pour the clean water with the mass of m into the sun-drying tank, and measure the water temperature t0 with a thermometer.
② Measure the area of the dry water tank cover with a scale. S. Turn the opening of the drying water tank to the direction perpendicular to the sunlight, cover the glass plate and start timing.
③ After time t, measure the water temperature.
(4) The radiation intensity of sunlight on the earth's surface is cm(t? t0)？ TS×50%
(3) During the experiment, many things are assumed, such as "assuming that the absorption of light by the glass plate can be ignored", "If the sunlight is always incident vertically during the experiment", "There is no loss of heat" and so on. This assumption will inevitably bring some influence to the final result. In addition, some factors, such as the change of ambient temperature caused by the change of weather during the experiment, have not been considered, so the measured results will be quite different from the real values.