要使处于基态的氢原子受激发后能发射赖曼系（由激发态跃迁到基态发射的各谱线组成的谱线系）的最长波长的谱线，至少应向基态氢原子提供的能量是（ ）。
A:
B:
C:
D:
A:
B:
C:
D:
举一反三
- 我国健康成年人血小板总数是（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/fecfc3776aee4bb5b377f5f8f9d9ee46.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/ab64ea1d8d134ba0845fb75e63a9a861.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/4841bf16bdb5469999b7c01b77c90325.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/14d1ed8474e5414591bc74e45bf0538a.png" />
- 假如电子运动速度与光速可以比拟，则当电子的动能等于它静止能量的2倍时，其德布罗意波长约为（ ）m。（普朗克常量<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/486718e348354f0f8706f38073d30016.png" />，电子质量<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/c39decde0930485fa409cb257f712e8a.png" />） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/e466e61658db48fc816f486d40ae959f.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/3a2fcc4c50a7410e807e4af3c59dcbc8.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/92443a569df04dee9598ae64e6aa3df9.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/21ffd61b214045ceac00daae77f7855f.png" />
- 如图所示，一束动量为 P 的电子，通过缝宽为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/b0abb5c99dbc4bec8b8315039bfee3d1.png" />的狭缝，在距离狭缝为 R 处放置一荧光屏，屏上衍射图样中央最大的宽度 d 等于（ ）。<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/8d94370bc8794b4ebf5f88e8d5bdcf62.png" /> A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/948caf37e15f4ae1a42fda70c455dcfd.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/07209cdf04d3491b9f214624bc9c0557.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/aa4fab6fa3e74ce6bd96b3e71c40fc30.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/e9fa48b360124287b56d549819645da5.png" />
- 当神经冲动到达运动神经末梢时，可引起接头前膜的（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/c84b709b9e9c4bb9a8b1942e8b41ae50.png" />通道开放 B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/05aeaddccf334079bf6c1268f2f1d915.png" />通道关闭 C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/3ad0962367574426ab5c55be38263105.png" />通道开放 D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/eacb0047877a43c5b10d8610ef234529.png" />通道开放
- 不同波长的电磁波有不同的频率，频率、波长与速度三者之间的关系为（）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/12388a4e000a493c9677667f96baec4e.png"/> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/448fcf95330149c6a5b533d950b29aa7.png"/> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201806/e18955c04da348178fc47edf20da8a20.png"/>