诗歌鉴赏
                                                                                             宿桐庐江寄广陵旧游①
                                                                                                        孟浩然
                                                                                          山暝听猿愁，沧江急夜流。
                                                                                          风鸣两岸叶，月照一孤舟。
                                                                                          建德②非吾土，维扬③忆旧游。
                                                                                          还将两行泪，遥寄海西头④。
注释：①旧游：指故交。②建德：今浙江省建德县一带。③维扬：即扬州。④海西头：指扬州。

如图，甲、乙是电磁学中很重要的两个实验，下列有关说法正确的是（   ）