大学MOOC Electromagnetic Field(Shandong University)1458234163 最新慕课完整章节测试答案

Exam of Electromagnetic Field Soure

1、单选题：

‍A  line charge density is given as   in the  arc line with a radius of a and a center angle of ， find the totel  quantity is

‎选项：
A:
B:
C:
D:
答案: 【 】

2、单选题：

‎Sheet charge density is given in cylindrical  coordinates as  in the regin ;for ,,find  the charge quantity of  the surface  z=0.1m.

‎选项：
A:
B:
C:
D:
答案: 【 】

3、单选题：

​Calculate the total charge with the volume charge density  in  universe

​选项：
A: 6.28C
B: 3.14C
C: 1.57C
D: 12.56C
答案: 【 6.28C】

4、多选题：
​Which description of current density  is right?‌
选项：
A: The current density is the amount of charge passing through the unit area vertically in unit time.
B: The current density is the amount of charge passing through any cross section in unit time.
C: The direction of current density is the direction of positron motion.
D: The direction of current density is the direction of electron  motion
答案: 【 The current density is the amount of charge passing through the unit area vertically in unit time.;
The direction of current density is the direction of positron motion.】

5、多选题：
‍About the line current, which following description is right?‍
选项：
A: Line current is a scalar.
B: Line current is a vector.
C: Line current describes the motion of the charge in the wire.
D: Line current only moves in or against the direction of  the wire.
答案: 【 Line current is a scalar.;
Line current describes the motion of the charge in the wire.;
Line current only moves in or against the direction of  the wire.】

Exam of Electric Field Intensity and Polarzation

1、单选题：

‍It is known that the charge density on the uniformly distributed surface of the semicircle with radius R as shown in the figure is . Assuming that the axial length of the semicircle is infinite and placed in vacuum, the electric field intensity E on the axis of the semicircle is

​

‍

​选项：
A:
B:
C:
D:
答案: 【 】

2、单选题：

‏If the inner and outer radii of two concentric metal spheres are a and b respectively, and the dielectric constant of the ideal dielectric is   between two metal spheres, the voltage between the inner and outer spheres is U, then the electric displacement vector D on the outer sphere surface (radius b) in the dielectric is

‎选项：
A:
B:
C:
D:
答案: 【 】

3、单选题：

‌The conductor radius of double wire transmission line is  5mm, and the distance between geometric axes is 1m. judge whether the air on the conductor surface be broken down as the voltage applied between conductors is 100kV. The breakdown field intensity of air is 

‎

‌

‎选项：
A: Yes
B: No
C: Can not be judged
D: Other three answers are all right
答案: 【 No】

4、单选题：
‍The flux of electric field intensity  E through a closed surface is equal to zero, which means in the surface‍
选项：
A: there are more positive charges than negative charges.
B: there are more negative charges than positive charges.
C: there are the same quantity of the positive charges and negative charges.
D: there is no polarized chargeharge.
答案: 【 there are the same quantity of the positive charges and negative charges.】

5、判断题：
‍The existence of polarized charge increases the electric field intensity in the medium.‌
选项：
A: 正确
B: 错误
答案: 【 错误】

Exam of Magnetici Field Intenstiy and Magnetization

1、单选题：
‏The unit of magnetic induction intensity is ‎
选项：
A:  Webermeter
B: Tesla
C: Ampere/meter
D:  Weber/meter
答案: 【 Tesla】

2、单选题：

‏An Infinite straight wire with radius a, the current denstiy flowing in it is , find  a the magnetic induction intensity of  ny point with distance b from wire axis ,  b>a outside the wire.

‌选项：
A:
B:
C:
D:
答案: 【 】

3、单选题：

‎Express the value of H in tectangluar components  at P(0,0.2,0) in the field  of a current filament 2.5A  in the  direction  at x=0.2, y= 0.3.

​选项：
A: 1.989+1.989
B: 1.899+1.899
C: 1.989-1.989
D: 1.899-1.899
答案: 【 1.989-1.989】

4、判断题：
‏When the medium is magnetized, the molecular magnetic moment inside the paramagnetic material turns to the opposite direction of the external magnetic field‎
选项：
A: 正确
B: 错误
答案: 【 错误】

5、判断题：
‎The magnetic field inside the magnetic medium is generated  by both conduction current and polarization current.‏‏‎‏
选项：
A: 正确
B: 错误
答案: 【 正确】