问题 选择题

在静电场中,下列说法正确的是:(         )

A.电势相等的地方,场强必定相等;

B.在场强处处相等的地方,电势不一定相等;

C.场强为零的点,电势必定为零;

D.在负点电荷形成的电场中,离电荷越近,电势越低,场强则越小。

答案

答案:B

电势与场强没有必然联系。电势相等的地方,场强不一定相等,场强处处相等的地方,电势不一定相等,场强为零的点,电势不一定为零,AC错B对。在负点电荷形成的电场中,由电场线分布可知,离电荷越近,场强越大。沿电场线方向电势降低,离负电荷越近,电势越低,D错。

阅读理解

Canada is a very large country.It is bigger than China.China is the third largest country in the world.Canada is the second largest.It has an area of nearly 10 million sq. km. Canada has a very long coastline.To the west is the Pacific Ocean.To the east is the Atlantic Ocean.The Arctic Ocean is in the north.There are very many islands off the Pacific coast and off the Arctic coast.The biggest one in the west is Vancouver Island.In the east there is New Foundland,and in the Arctic Ocean the biggest islands are Baffin Island and Victoria Island.(Greenland is not part of Canada.It is a part of Denmark,a country in northern Europe.)

Canada has a long border with the U.S.A.in the south.In the northwest Canada borders on the American“State of Alaska”.Canada is a northern country.The Arctic Circle is (Latitude 16°N) passes through the northern part.In the south,half of the border with the U.S.A. follows line of latitude 49°N.

小题1:Which of the following statements is true?

A.U.S.A is the second largest country in the world.

B.Canada has nearly 10 million sq. km.So it is the second largest country on the earth.

C.China is as large as Canada and the second largest in the world.

D.Russia is the second largest country in the world.小题2:What ocean is in the north of Canada?

A.The Pacific Ocean.

B.The Atlantic Ocean.

C.The Indian Ocean.

D.The Arctic Ocean.小题3:There are many islands in Canada,and Vancouver Island is ________.

A.in the west

B.in the east

C.in the north

D.in the south

单项选择题