課程名稱︰材料科學導論二
課程性質︰必帶
課程教師︰郭博成教授
開課學院：工學院
開課系所︰材料系
考試日期（年月日）︰99/06/22
考試時限（分鐘）：14:30~16:30
是否需發放獎勵金：yes
（如未明確表示，則不予發放）
試題 :
(All of them are old questions...)
1.(a)Explain the origins of the magnetic moment of an atom.
(b)Do all electrons have a net magnetic moment? Why or why not?
(c)Do all atoms have a net magnetic moment? Why or why not?
(15%)
2.Briefly describe the differences among diamagnetism, paramagnetism,
ferromagnetism, antiferromagnetism, and ferrimagnetism.
(20%)
3.Illustrate the boundart in T-H-J (temperature-magnetic field-current density)
space seperating superconducting states and normal states.
(20%)
4.Explain why the resistivity of metal is increased with temperature but the
resistivity of intrinsic semiconductor is decreased with increasing
temperature.
(15%)
5.How does the electron structure of an isolated atom differ from that of a
solid material?
(10%)
6.Some hypothetical metal is known to have an electric resistivity of 4x10^8
(ohm-m). Through a specimen of this metal that is 25mm thick is passed a
current of 30A; when a magnetic field of 0.75 tesla is simultaneously imposed
in a direction perpendicular to that of the current, a Hall voltage of
-1.26x10^-7 V is measured.
(a) Compute the electron mobility for this metal,and
(b) the number of free electrons per cubic meter.
(20%)
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