矩形线圈在匀强电场中匀速转动，产生的变电动势
，若该线圈电阻不计，外接总电阻为
的负载，则（ ）
A．该交流电的频率为
B．负载的电功率是
C．用交流电压表和电流表可测得负载两端电压为
，流过负载的电流是
D．当
时，线圈中的电动势均为最大值
答案：D
根据表达式有最大值为200V，有效值为
V，频率为10Hz，AC错误；功率
，B错误；当
时，代入表达式得200V，D正确。
| 完形填空。 | ||||
| Lie Yu Kou (Lie Zi) was showing Bo Hun Wu Ren his archery(射箭) skill. He 1 the bow to its full extent, had a cup of water 2 on his elbow, and released the arrow. As soon as the first arrow flew off, a second one was wound up. The moment the second one was winged, a third was ready, and all of them lodged in the same place. During all this time, his 3 was as still as a statue. After his performance, Lie Zi asked Bo Hun Wu Ren: "What do you think of my archery skill?" Bo Hun Wu Ren laughed: "This is still only a(an) 4 shot, not quite the perfect shot yet. Let's climb up the mountain and stand on the 5 overhanging the abyss(深渊). We'll see if you can 6 an arrow." Wu Ren then led Lie Zi up to a place eight hundred feet above a deep valley. Wu Ren turned his 7 to the edge of the cliff, 8 moving his feet until he was standing with his heels extending over the edge, and 9 Lie Zi to join him. Lie Zi was so 10 that he threw himself down on the ground, sweating from head to toe. Bo Hun Wu Ren raised the bow and shot the arrows from his bow, with no 11 missed. Then he looked at Lie Zi and said 12 . " The best archer can look up at the blue 13 , down at the nether (地下的) world and to the eight poles of the earth but still keep 14 . Here on this mountain, you're already 15 , so your chances of hitting your mark are very slim". | ||||
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