问题 选择题

下列说法中正确的是(  )

A.电磁波具有偏振现象,说明电磁波是纵波

B.变化的磁场一定产生电场

C.机械波和电磁波都能发生反射、折射、干涉和衍射等现象,是因为它们都可以在真空中传播

D.光速不变原理和时间间隔的相对性是狭义相对论的两个基本假设

答案

A、电磁波具有偏振现象,说明电磁波是横波.故A错误;

B、根据麦克斯韦的电磁场理论,在变化的电场周围一定产生磁场,只有非均匀变化的电场周围才产生变化的磁场;在变化的磁场周围一定产生电场,只有非均匀变化的磁场周围才产生变化的电场.故B正确;

C、机械波和电磁波都能发生反射、折射、干涉和衍射等现象,但机械波不能在真空中传播.故C错误.

D、狭义相对论的两个基本假设是相对性原理和光速不变原理.故D错误.

故选:B

开放性试题

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① 学习方面主要遇到哪些困难、挫折:

                                                                                                                                                              

你采取的应对办法: 

                                                                                                                                                             

结果:

                                                                                                                                                             

② 交往方面的困难、挫折:

                                                                                                                                                              

你采取的应对办法: 

                                                                                                                                                             

结果:

                                                                                                                                                              

单项选择题