如图所示,在直角坐标系的第Ⅱ象限和第Ⅳ象限中的直角三角形区域内,分布着磁感应强度

题型:问答题

问题:

如图所示,在直角坐标系的第Ⅱ象限和第Ⅳ象限中的直角三角形区域内,分布着磁感应强度均为B=5.0×10-2T的匀强磁场,方向分别垂直纸面向外和向里.质量为m=6.64×10-27㎏、电荷量为q=+3.2×10-19C的α粒子(不计α粒子重力),由静止开始经加速电压为U=1205V的电场(图中未画出)加速后,从坐标点M(-4,

2
)处平行于x轴向右运动,并先后通过匀强磁场区域.

(1)请你求出α粒子在磁场中的运动半径;

(2)请你在图中画出α粒子从直线x=-4到直线x=4之间的运动轨迹,并在图中标明轨迹与直线x=4交点的坐标;

(3)求出α粒子在两个磁场区域偏转所用的总时间.

考点:向心力牛顿第二定律动能定理带电粒子在电场中运动的综合应用带电粒子在匀强磁场中的运动
题型:问答题

口腔医务人员感染乙肝病毒的几率是普通人的

A.1倍

B.2倍

C.5倍

D.10倍

E.25倍

题型:问答题

患者当出现圆脸、厚背、躯干发胖而四肢消瘦的“向心性肥胖”特殊体形时,提示

A.甲状腺激素分泌过多

B.生长激素分泌过多

C.糖皮质激素分泌过多

D.肾上腺素分泌过多

E.胰岛素分泌不足

题型:问答题

The following data sufficiency problems consist of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of counterclockwise), you must indicate whether.

In the figure above, is AB>BC ?()(Note: Figure not necessarily drawn to scale.)

(1) AB>CD

(2) (AD-AB)>(AD-BC)

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

题型:问答题

人口疏散的时机如何掌握?

题型:问答题

什么叫国有土地使用权?

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