做法表演前,准备1个铁架台、1块铁片、1粒樟脑球、1根小树枝、1只玻璃杯、1块毛巾、1支蜡烛和1盒火柴。表演时,把铁皮固定在铁架台上,并在铁片上放上樟脑球和小树枝,用玻璃杯罩住,如图1。再在玻璃杯上盖上毛巾,然后再用火柴点燃蜡烛,移至铁片下加热。过一会儿,停止加热。稍微冷却后,揭开毛巾,拿开玻璃杯。这时,观众就会看到,玻璃杯里的树枝上有一层皑皑的白雪。原理 Before the performance, prepare a metal platform, a piece of iron, a camphor ball, a twig, a glass, a towel, a candle, and a box of matches. During the performance, the iron sheet was fixed on the iron stand, and the camphor balls and twigs were placed on the iron sheet and covered with a glass cup, as shown in Figure 1. Then cover the glass with a towel, then use the match to light the candle and move it under the iron plate to heat it. After a while, stop heating. After cooling slightly, uncover the towel and remove the glass. At this time, the audience will see a bright white snow on the branches in the glass. principle