在进行课堂演示实验、滴定分析、目视比色分析时,因光线弱、观察者距离较远等原因,使学生在观察物质的颜色是否发生变化及变化的程度,沉淀是否产生与产生沉淀的多少等实验现象时往往不准确。如果在灯光屏前做实验,则能使实验现象更鲜明突出。 In the classroom demonstration experiment, titration analysis, visual colorimetric analysis, due to weak light, distant observers and other reasons, so that students observe whether the color of the material changes and the degree of change, precipitation and precipitation How many experimental phenomena are often inaccurate. If you do experiments in front of the light screen, you can make the experimental phenomenon more prominent.