Scientists cant yet make an invisibility cloak1 like the one that Harry Potter2 uses.But,for the first time,theyve constructed a simple cloaking device that makes itself and somethingplaced inside it invisible to microwaves. Invisibility isnt possible yet with waves of light that the human eye can see.But it is nowpossible with microwaves.Like visible light,microwaves are a form of radiant energy.Theyare part of the electromagnetic spectrum,which also includes radio waves,infrared light,ultraviolet rays,X rays,and gamma rays.The wavelengths of microwaves are shorter thanthose of radio waves but longer than those of visible light. To a detector set up to receive microwaves on the other side of the ring,it looks as if thewaves never changed their paths as if there were no object in the way! So,the ring is effectively invisible. 练习: Acan now make an invisible cloak of the same kind as he uses. Ctry to invent a device Similar in idea to the invisible cloak he uses.
河北省2016届高考英语一轮复习学案(新人教版) Unit 1《Great Scientists》必修5
河北省2016届高考英语一轮复习学案(新人教版) Unit 3《Travel journal》必修1
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2016届高考英语一轮复习对点练习:选修8 Unit 1《A land of diversity》
2016高考英语人教新课标选修6—U2学生选练(2)及答案
2016高考英语人教新课标选修6—U2学生选练(3)及答案
河北省2016届高考英语一轮复习学案(新人教版) Unit 3《A taste of English humour》必修4
河北省2016届高考英语一轮复习学案(新人教版) Unit 1《Festivals around the world》必修3
2016高考英语人教新课标选修6-U5一轮测试精品及答案
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2016高考英语人教新课标选修6—U5学生选练(2)及答案
2016届高考英语一轮复习对点练习:选修8 Unit 3《Inventors and inventions》
2016高考英语人教新课标选修6—U4学生选练(3)及答案
河北省2016届高考英语一轮复习学案(新人教版) Unit 3《Computers》必修2
河北省2016届高考英语一轮复习学案(新人教版) Unit 4《earthquake》必修1
2016届高考英语一轮复习对点练习:选修7 Unit 4《Sharing》
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山西省2016届高考英语一轮复习学案(新人教版) Uint 3《Under the sea》选修7
2016届高考英语一轮复习对点练习:选修7 Unit 5《Travelling abroad》
河北省2016届高考英语一轮复习学案(新人教版) Unit 2《English around the world 》必修1
河北省2016届高考英语一轮复习学案(新人教版) Unit 2《working the land》必修4
2016高考英语人教新课标选修6-U1一轮测试精品及答案
河北省2016届高考英语一轮复习学案(新人教版) Unit 3《Life in the future》必修5
2016高考英语人教新课标选修6-U4一轮测试精品及答案
2016高考英语人教新课标选修6—U1学生选练(1)及答案
山西省2016届高考英语一轮复习学案(新人教版) Uint 4《Earthquake》必修1
河北省2016届高考英语一轮复习学案(新人教版) Unit 4《Body language》必修4
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