[試題] 102下 趙治宇 普通物理學甲下 期中考

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課程名稱︰普通物理學甲下
課程性質︰必修
課程教師︰趙治宇
開課學院：工學院
開課系所︰機械系
考試日期（年月日）︰2014/04/24
考試時限（分鐘）：120
是否需發放獎勵金：是
（如未明確表示，則不予發放）

試題 :

1.Describe the working principle of scan tunneliung microscope.(12%)

2.Describe the operating principle of time-of-flight mass spectroscopy.(12%)

3.Explain the phenomenon of Hall effect and its importance.(14%)

4.Consider a straight section of wire of length l,as in Fig.1,which carries
  a current I. Show that the magnetic field at point P a distance R from
  the wire along its perpendicular bisector is

  B=μI/2πR*l/(l^2+4R^2)^1/2


       ▌
   1/2l▌↑I
       ▌       R
       ▌—————→P
       ▌
   1/2l▌                   (12%)
       ▌

5.Figure2 shows a parallel-plate capacitor of plate area A=12.5cm^2 and plate
  separation 2d=7.12mm. The left half of the gap is filled with material of
  dielectric constantκ1=21.0 ; the top of the right half is filled with
  material of dielectric constantκ2=42.0; the bottom of the right half is
  filled with material of dielectric costantκ3=58.0. What is the capacitance?
                                                             (12%)
       ▃▃▃▃▃▃▃▃▃▃
                 ▏  κ2
   2d      κ1   ▏▁▁▁▁
                 ▏  κ3
       ▃▃▃▃▃▃▃▃▃▃
          A/2        A/2


6.In Fig.3, current is set up through atruncated rught circular cone of
  resistivity 731Ω*m, left radius a=2.00mm, right radius b-2.30mm, and
  length L=1.94cm. Assume that the current density is umoform across any
  section talen perpendicular to the length. What is the resistance of
  the cone?  (14%)

                 ◢
               ◢█
             ◢██
           ◢███
           ████
           ████
        a  ████ b
           ████
           ◥███
             ◥██
               ◥█
                 ◥
          ∣←L→ ∣

7. In Fig.4, the current in resistance 6 is i6=1.40A and the resistance are
   R1=R2=R3=2.00Ω,R4=16.0Ω,R5=8.00Ω, and R6=4.00Ω.What is the emf of the
   ideal battery?(12%)

            R1          R2          R5
      ┌──﹏──┬──﹏──┬──﹏──┐
     +│          │          │          │
      ＝          ︴R3        ︴R4        ︴R6 ↓I6
     _│          │          │          │
      └─────┴─────┴─────┘


8.A 13.0g wire of length L=62.0cm is suspended by a pair of flexible leads
  in a uniform magnetic field of magnitude 0.440T(Fig.5). What are the
  (a) magnitude and (b) direction (left or right) of the current required
  to remove the tension in the supporting leads?(12%)

    ─────────────────────
          ▌                           ▌
          ︴                           ︴
          ︴  X   X   X   X    X   X   ︴
          ︴            L              ︴
          ︴▂▂▂▂▂▂▂▂▂▂▂▂▂ ︴

             X   X   X   X   X   X   X

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