本课配套习题挑战模式1/5
单选题
难度系数:
1.关于无线电波的主要用途,下列说法正确的是( )
A: 收音机用中波 |
B: 超远程通信只能用微波 |
C: 电视机发射、接收用的是长波 |
D: 移动通信用中短波 |
一次做对,真牛!
+5奖励规则>
- 提示1:5LqG6Kej55S156OB5rOi55qE5bqU55So
- 答案:QQ==
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本课配套习题挑战模式2/5
单选题
难度系数:
2.小冬等几位同学,在放学回家的路上,经过广播电视台,看到高高的发射天线,他们有以下几种说法,你认为不正确的是( )
A: 无线电波要通过天线向外发射到空中 |
B: 发射无线电信号时,要将音频电信号加载到高频电磁波上 |
C: 收音机的调谐器可以从电磁波中选出特定频率的信号 |
D: 收音机中的扬声器能把电磁波转换成声音 |
一次做对,真牛!
+5奖励规则>
- 提示1:5pS26Z+z5py655qE5oms5aOw5Zmo5oqK6Z+z6aKR5L+h5Y+36L2s5o2i5oiQ5aOw6Z+z
- 答案:RA==
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本课配套习题挑战模式3/5
单选题
难度系数:
3.中央人民广播电台第二套节目的发射频率是720kHz,女播音员发声的频率约为1kHz,那么收音机接收时,调谐器选择的频率应为( )
A: 721kHz |
B: 720kHz |
C: 719kHz |
D: 1kHz |
一次做对,真牛!
+5奖励规则>
- 提示1:NzIwS0h65oyH55qE5piv55S156OB5rOi6aKR546H77yMMUtIeuaYr+WjsOmfs+mikeeOhw==
- 答案:Qg==
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本课配套习题挑战模式4/5
单选题
难度系数:
4.能把声音和图像转化为变化的电流的装置是( )
A: 话筒,摄像机 |
B: 话筒,显像管 |
C: 扬声器,显像管 |
D: 扬声器,摄像机 |
一次做对,真牛!
+5奖励规则>
- 提示1:5LqG6Kej5ZCE56eN5L+h5Y+35LmL6Ze055qE6L2s5YyW
- 答案:QQ==
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本课配套习题挑战模式5/5
单选题
难度系数:
5.关于移动电话,下列叙述正确的是( )
A: 移动电话就是固定电话 |
B: 移动电话只可以接收电磁波 |
C: 移动电话既可以发射电磁波,又可以接收电磁波 |
D: 移动电话的工作原理与固定电话的工作原理完全一样,没有区别 |
一次做对,真牛!
+5奖励规则>
- 提示1:56e75Yqo55S16K+d5LiO5Zu65a6a55S16K+d55qE5bel5L2c5Y6f55CG5Z+65pys55u45ZCM77yM5L2G5Zyo5L+h5Y+35Lyg6L6T546v6IqC5pyJ5piO5pi+5Yy65Yir
- 答案:Qw==
56e75Yqo55S16K+d5LiO5Zu65a6a55S16K+d55qE5bel5L2c5Y6f55CG5Z+65pys55u45ZCM77yM5L2G5Zyo5L+h5Y+35Lyg6L6T546v6IqC5pyJ5piO5pi+5Yy65Yir77yb5Zu65a6a55S16K+d5py65piv6Z2g5a+857q/5Lit55qE5L+h5Y+355S15rWB5p2l5Lyg6YCB5L+h5Y+377yM6ICM56e75Yqo55S16K+d5pei5piv5peg57q/55S15Y+R5bCE5Y+w77yM5Y+I5piv5peg57q/55S15o6l5pS25Y+w77yM6Z2g5peg57q/55S15rOi5Lyg6YCB5L+h5oGv77yO5pWF6YCJQ++8jg==