b5u1 Reading great scientists 公开课优质课件.ppt

Para.1 John Snow was a famous doctor in London-so expert, indeed, that he attended Queen Victoria as her personal physician. But he became inspired when he thought about helping ordinary people exposed to cholera. This was the deadly disease of its day. Neither its cause nor its cure was understood. So many thousands of terrified people died every time there was an outbreak. John Snow wanted to face the challenge and solve this problem. He knew that cholera would never be controlled until its cause was found. What might cause cholera? John snow---a doctor, Queen Victoria as her personal physician. But he was willing to help ordinary people cholera. Many people died every time there was an . He wanted to face the and solve the problem. Two theories caught his attention. The first suggested that cholera multiplied in the air. The second suggested that people this disease into their bodies and the disease attacked the body. John Snow the second was right but he needed evidence. When another outbreak hit London in 1854, he was ready to begin his and tried to get information. He found that most of the deaths were near a water pump and the spread of the disease was 8 water. With the evidence, he was able to that polluted water carried the virus. After that, he suggested the source of all the water supplies be examined. Finally “King Cholera” was . 爱迪生发明电灯 以前，油灯。这种灯有浓烈的黑烟和刺鼻的臭味。更严重的是，这种灯很容易引起火灾。爱迪生想发明一种既安全又方便的电灯。 首先选择用碳丝做灯泡，很快就失败了，但他却发现灯泡内必须是真空状态。随后选择用熔点较高的白金，但它的燃烧时间仍然很短。爱迪生并不气馁，先后试用了钡、钛、锢等各种稀有金属，效果都不很理想。 爱迪生总结了之前试过的材料，有1600种之多。终于，他发现竹丝燃烧的时间更长，1200个小时。到1906年，爱迪生又改用钨丝来做，使灯泡的质量又得到提高，一直沿用到今天。 当人们点亮电灯时，每每会想到这位伟大的发明家，是他，给黑暗带来无穷无尽的光明。 Edison invented electric bulb Find the problem: Make up a question The method to do it: Analyze the result: Draw a conclusion: oil lamp had disadvantages (dark, dirty, f