试题与答案

如图所示,理想变压器原线圈输入交流i=Imsinωt,副线圈按有一电流表和负载电

题型:选择题

题目:

如图所示,理想变压器原线圈输入交流i=Imsinωt,副线圈按有一电流表和负载电阻R,电流表的示数为0.10A.在t=时(T为交流的周期),原线圈中的电流瞬时值为0.03A.变压器的原、副线圈的匝数比为(  )

A.10:3

B.3:10

C.3:10

D.10:3

答案:

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题型:阅读理解

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a higher jump. He would jump again and again until he made it!

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A. Beijing    

B. Shanghai    

C. Guilin        

D. chongqing

2. Liu Xiang was too ______ to do the high jump.

A. tall        

B. high        

C. little        

D. short

3. Liu met his coach Sun Haiping when he was ______ .

A.14          

B. 15        

C. 16          

D. 17

4. Liu's speed (速度) at the 2004 Summer Olympics was ______.

A. 12.91      

B. 12.88    

C. 12.61      

D. 12.96

5. On July 12,2006, Liu  ______ in the 110-meterhurdles.

A. broke the rules            

B. set a new world record

C. equaled the world record    

D. did badly

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题型:选择题

如图,两根互相平行的长直导线过纸面上的M、N两点,且与纸面垂直,导线中通有大小相等、方向相反的电流.a、o、b在M、N的连线上,o为MN的中点,c、d位于MN的中垂线上,且a、b、c、d到o点的距离均相等.关于以上几点处的磁场,下列说法正确的是(  )

A.o点处的磁感应强度为零

B.a、b两点处的磁感应强度大小相等,方向相反

C.c、d两点处的磁感应强度大小相等,方向相同

D.a、c两点处磁感应强度的方向不同

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