问题 选择题

下列关于感应电动势的说法正确的是(  )

A.闭合回路中的磁感应强度越大,感应电动势越大

B.闭合回路中的磁通量越大,感应电动势越大

C.闭合回路中的磁通量变化越大,感应电动势越大

D.闭合回路中的磁通量变化越快,感应电动势越大

答案

A、闭合回路的磁感应强度大,磁通量的变化率不一定大,即感应电动势不一定大,故A错误.

BCD、据法拉第电磁感应定律可知:感应电动势的大小与穿过电路的磁通量的变化率成正比,并不是与磁通量、磁通量的变化成正比,故BC错误,D正确.

故选:D.

阅读理解

阅读理解

     The Queen's English is now sounding less upper-class, a scientific study of the Queen's Christmas

broadcasts had found.Researchers have studied each of her messages to the Commonwealth countries

since 1952 to find out the change in her pronunciation from the noble Upper Received to the Standard

Received.

     Jonathan Harrington, a professor at Germany's University of Munich , wanted  to  discover whether

accent (口音 ) changes  recorded over the past half century would take place within one person. "As

far as I know,there just is nobody else for whom there is this sort of

broadcast records, " he said.

     He said  the  noble  way  of  pronouncing  vowels (元音 ) had gradually lost ground as the noble

upper-class accent over the past years. "Her accent sounds slightly less noble than it did 50 years ago.

But these are very, very small and slow changes that we don't notice from year to year.

     " We may be able to relate it to changes in the social classes, " he told The Daily Telegraph, a British

newspaper. "In 1952 she would have been heard saying  'that men in the black hat ' . Now it would be 

 ' that man in the black hat ' . Similarly, she would have spoken of ' the  citay ' and  ' dutay ' , rather than

' citee ' and ' dutee '  , and  ' hame '  rather than  'home'. In the 1950s she would have been 'lorst', but by

the  1970s  'lost'."

     The Queen's broadcast is a personal message to the Commonwealth countries. Each Christmas, the

l0-minute broadcast is put on TV at 3 p. m. in Britain as many families are recovering from their traditional turkey lunch(传统火鸡午餐 ) .

     The results were published  (发表 )  in the Journal of Phonetics.

1. The Queen's broadcasts were chosen for the study mainly because________.    

A. she has been Queen for many years

B. she has a less upper-class accent now

C. her speeches are familiar to many people

D. her speeches have been recorded for 50 years

2. Which of the following is an example of a less noble accen in English?____________

A. dutay        

B. citee        

C. hame        

D. lorst

3. We may infer from the text that the Journal of Phonetics is a magazine on____________.

A. speech sounds          

B. Christmas customs

C. TV broadcasting        

D. personal messages

4. What is the text mainly about? ___________

A. The relationship between accents and social classes.

B. The Queen's Christmas speeches on TV.

C. The changes in a person's accent.

D. The recent development of the English language.

问答题 简答题