一矩形单匝刚性线圈与二线输电线位于同一平面上，有关几何尺寸如_爱下问搜题

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问题单项选择题

一矩形单匝刚性线圈与二线输电线位于同一平面上，有关几何尺寸如试题3-16图所示，若二回路中分别通有电流I₁和I₂，则刚性线圈受力的大小为（）。

A.

B.

C.

D.

答案

参考答案：C

解析：

由于在同一平面上，积分很方便。求I₁在刚性线圈产生的磁通φ，则二回路间互有能W_m=φI₂，再用虚位移公式对a求导得力。

也可以通过φ求得M=φ/I₁，再求互有能W_m=MI₁I₂。

填空题

世界上面积最多的大洋是________，世界上跨海拔最高的大洲是_______。

完形填空

A boy of 14 has become the youngest student to win a place at Cambridge University. Arran Fernandez, who was 16 at home by his father, Neil, will 17 a mathematics degree at Fitzwilliam College next month and he hopes to have a career as a research mathematician to 18 the Riemann hypothesis(黎曼猜想) that has confused the brightest minds. It will make him the youngest Cambridge student 19 14-year-old William Pitt the Younger studied there in 1773.
Last night the child genius said: “I am looking forward to going to the 20 . I have started the first-year books  21   and it is all right, not too 22 . I can understand it. I am excited about going to Cambridge, 23 I am used to making records about being the youngest in education. It isn’t the youngest moment that is so important to me-- 24 I’m more interested in going to Cambridge than comparing   25 with other people who go there.”
But 26 his age he will not be able to    27 many of the alcohol-fuelled festivities(庆典) traditionally  28 to Freshers’ Week. “I don’t think I’m missing too much fun,” he insisted. “Even if I was 18, I wouldn’t want to go out  29 . ”
Arran, 30   plans to join the bird-watching society instead and go boating while at university, was five when he 31  the youngest person to be 32   a GCSE (General Certificated of Secondary Education), after passing maths. He was offered the   33  to learn at Cambridge in 2010, when he was 14, on the condition he gained an A-level in physics, which he  34 with an A+ grade. Arran had already gained an A grade in further maths last year.
Cambridge also asked him to attend three GCSEs in subjects which were not related to maths and physics to  35   his knowledge. He gained A+s in English literature and French and an A in English language this summer.

A．festivities

C．interesting

C．additionally

A．fortunately

D．opportunity

D．represented