简介:中考模拟试题(一)一、单项选择题(每小题2分,共30分)1.下列对一些物理量的估计基本符合实际的是()A.你用的物理课本的长度大约是0.40mB.通过书写台灯的电流大约是0.18A
简介:Duringthelaterpartofthe19thcentury,physi-cistshadbegunexperimentingwithphenomenaarisingfrompassinganelectriccurrentthroughgasesatlowpressure.Undertheseconditionscathoderays①fromthenegativeelectrodetothepositiveelectrodeofadis-chargeorvacuumtube.In1895,attheageof50,Wil-helmRoentgen②enteredthisnewfieldofresearch.