课程名称︰普通物理学甲下
课程性质︰必修
课程教师︰赵治宇
开课学院：工学院
开课系所︰机械系
考试日期（年月日）︰2014/04/24
考试时限（分钟）：120
是否需发放奖励金：是
（如未明确表示，则不予发放）
试题 :
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