问题 选择题

图甲是某燃气炉点火装置的原理图。转换器将直流电压转换为图乙所示的正弦交变电压,并加在一理想变压器的原线圈上,变压器原、副线圈的匝数分别为。V为交流电压表。当变压器副线圈电压的瞬时值大于2500V时,就会在钢针和金属板间引发电火花进而点燃气体。以下判断正确的是

A.电压表的示数等于5V

B.电压表的示数等于

C.实现点火的条件是

D.实现点火的条件是

答案

BD

题目分析:由图乙可知变压器初级电压最大值为5V,则有效值为,即电压表的示数等于;要想点火则变压器次级电压要达到2500V,根据,解得,所以实现点火的条件是

选项BD正确。

问答题 简答题
单项选择题

It is incongruous that the number of British institutions offering MBA courses should have grown by 254 percent during a period when the economy has been sliding into deeper recession. Optimists, or those given to speed, assumptions, might think it marvelous to have such a resource of business school graduates ready for the recovery. Unfortunately, there is now much doubt about the value of the degree not least among MBA graduates themselves, suffering as they are from the effects of recession and facing the prospect of shrinking management structures.

What was taken some years ago as a ticket of certain admission to success is now being exposed to the scrutiny of cost-conscious employers who seek "can-dos" rather than "might-dos", and who feel that academia bas not been sufficiently appreciative of the needs of industry or of the employers’ possible contribution.

It is curious, given the name of the degree, that there should be no league table for UK business schools; no unanimity about what the degree should encompass; and no agreed system of accreditation. Su rely there is something wrong. One wonders where all the tutors for this massive infusion of business expertise came from and why all this mushrooming took place.

Perhaps companies that made large investments would have been wiser to invest in already existing managers, perched anxiously on their own internal ladders The Institute of Management’s 1992 survey, which revealed that eighty-one per cent of managers thought they personally would be more effective if they received more training, suggests that this might be the case. There is, too, the fact that training alone does not make successful managers. They need the inherent qualifications. Of character; a degree of self-subjugation; and above all, the ability to communicate and lead; more so now, when empowerment is a buzzword that is at least generating genuflexions, if not total conviction.

One can easily think of people, some comparatively unlettered, who are not lauded captains of industry. We may, therefore, not need to be too concerned about the fall in applications for business school places, or even the doubt about MBAs. The proliferation and subsequent questioning may have been an inevitable evolution. If the Management Charter Initiative, now exploring the introduction of a senior management qualification, is successful, there will be a powerful corrective.

We believe now that management is all about change. One hopes there will be some of that in relationship between management and science within industry, currently causing concern and which is overdue for attention. No-one doubts that we need more scientists and innovation to give us an edge in an increasingly competitive world. If scientists feel themselves undervalued and under-used, working in industrial ghettos, that is not a promising augury for the future. It seems we have to resolve these misapprehensions between science and. industry. Above all, we have to make sure that management is not itself smug about its status and that it does not issue mission statements about communication without realizing that the essence of it is a dialogue. More empowerment is required and we should strive to achieve it.

According to the passage, employers()

A. feel that they have not been consulted sufficiently about their needs

B. consider that cost-consciousness is the most important qualification

C. are more concerned about the value of the degree than graduates themselves

D. feel that MBAs will not be necessary because of shrinking management structures