试题与答案

在暗室的真空装置中做如下实脸:在竖直放置的平行金属板间的匀强电场中,有一个能产生

题型:问答题

题目:

在暗室的真空装置中做如下实脸:在竖直放置的平行金属板间的匀强电场中,有一个能产生三种射线源、从射线   源射出的一束射线垂直于电场方向射入电场,如图所示,在于射线源距离为H高处,水平放置两张叠放着的、涂药面朝下的印像纸(比一般纸厚且坚韧的涂有感光药的纸),经射线照射一段时间后把两张印像纸显形。

(1)上面的印像纸有几个暗斑?各是什么射线的痕迹?

(2)下面的印像纸显出一串三个暗斑,试估算中间暗斑与两边暗斑的距离之比?

(3)若在此空间再加上与电场方向垂直的匀强磁场,一次使射线不偏转,一次使射线不偏转,则两次所加匀强磁场的磁感应强度之比是多少?(已知:)

 

答案:

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题型:单项选择题

The questions in this group are based on the content of a passage. After reading the passage, choose the best answer to each question. Answer all questions following the passage on the basis of what is stated or implied in the passage.

One of the biggest questions facing the art world today is the dilemma over the repatriation of cultural treasures. Although the subject has not been widely noted by the general public, in recent decades museums and art dealers have repeatedly faced off against the representatives of nations and ethnic groups whose cultural legacies have been robbed by the rapacious collecting of these so-called art experts. Advocates of repatriation have argued that cultural treasures should be returned to their nations of origin, both because of basic fairness and because the artwork and cultural artifacts in question are best understood within their local context.

Several prominent museums, most notably the British Museum in London and the Louvre in Paris, have defended themselves on the grounds that they can better protect and preserve these cultural treasures than can the developing nations and impoverished ethnic groups that frequently seek their return. They further argue that more people can see the treasures if they are proudly displayed in a major museum, as opposed to some poorly funded national museum in a backwater country; evidently, the quantity of viewers is more important than the relevance of the art and artifacts to the viewer.

The arguments of the museum curators fall apart in an instance such as the Elgin Marbles. These majestic marble sculptures, which once graced the Parthenon on the Acropolis in Athens, were stolen by Lord Elgin in the nineteenth century and given to the British Museum, which holds them to this day. The people of Athens have built a beautiful, modern museum on the Acropolis to display the Elgin Marbles and other treasures from the Greek cultural heritage, so there can be no valid argument that the Greeks are unable to house the sculptures properly. Furthermore, more people visit the Acropolis every day than visit the British Museum.

The third paragraph plays what role in the passage ?()

A. It summarizes all the points expressed in the first two paragraphs.

B. It raises new arguments that expand on those previously expressed.

C. It suggests a possible area for useful research in the future.

D. It rejects the arguments expressed in the first paragraph.

E. It provides concrete evidence against arguments expressed in the second paragraph.

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