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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. | 
