问题
计算题
如图所示，ABCD是一个正方形的匀强磁场区域，由静止开始经相同电压加速后的甲、乙两种带电粒子，分别从A、B两点射入磁场，结果均从C点射出，则它们的速率v甲︰v乙为多大？，它们通过该磁场所用的时间t甲︰t乙为多大？
答案
1:2 ；2:1
题目分析：根据
得
洛仑兹力关系：推得
由
得比荷的比：
由
，
；从
搜题请搜索小程序“爱下问搜题”
如图所示，ABCD是一个正方形的匀强磁场区域，由静止开始经相同电压加速后的甲、乙两种带电粒子，分别从A、B两点射入磁场，结果均从C点射出，则它们的速率v甲︰v乙为多大？，它们通过该磁场所用的时间t甲︰t乙为多大？
1:2 ；2:1
题目分析：根据得
洛仑兹力关系：推得
由 得比荷的比：
由，；从
| 阅读理解。 | ||
| Across the United States, there are several places where two independent towns grew together to become one city-but kept both their names.
of one of Reynolds' best-known cigarette brands. Fast-growing Winston soon surrounded the much older town of Salem, so in 1913, people in the area voted to combine them into a single place. From a historical and tourist point of view, Salem, or Old Salem, as it's called today, is the interesting and unusual part of town. Salem was founded in the 1700s by the Moravians. They spoke German, and their community was religiously based, with single men and single women living apart in separate dormitories. The Moravians greatly valued women's work and brainpower. In fact, one of the nation's oldest boarding schools for young women-the Moravians' Salem Academy founded in 1772-is still in operation. Over the years, Salem lost its Moravian character. That all changed, though, when a nonprofit group began to rehabilitate the historic area These days Old Salem is what's called a living history museum, with exhibits, music, and tours of 18th-century houses, taverns and Moravian dormitory buildings just seven blocks from the tallest skyscraper in Winston-Salem. The historic community is booming again, Just as R J. Reynolds is taking in millions of dollars making cigarettes across town, Old Salem is generating about $15 million a year in tourism revenue and donations. | ||
| 1. From the passage we can know that _____. | ||
[ ] | ||
| A. Winston-Salem is the name of a city B. Salem is home to the tobacco market C. the city Winston-Salem has two names D. Old Salem is the name of a tobacco brand | ||
| 2. It can be inferred from Paragraph 3 that _____. | ||
[ ] | ||
| A. the two cities benefited each other B. Salem developed faster than Winston C. R J. Reynolds Company has moved into Salem D. the combination meets the wishes of the people | ||
| 3. The city Salem is special for its _____. | ||
[ ] | ||
| A. boarding school B. lifestyle and tradition C. respect for brainpower D. religious belief | ||
| 4. The underlined word "rehabilitate" in Paragraph 6 is closest in meaning to "_____". | ||
[ ] | ||
| A. reconstruct B. evaluate C. enlarge D. decorate | ||
| 5. What will probably be talked about in the following part? | ||
[ ] | ||
| A. Some other attractions in Winston-Salem. B. How Winston makes profits from tourism. C. Other examples of cities combined by two parts. D. Something about the boarding school for women. |
