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）︰2016/6/23
考试时限（分钟）：170分钟
试题 :
1.What's the working principle of tape recording and playback in a video tape
recorder?(4%,4%)
2.Derive the radiation Pr=I/c (total absortion) and Pr=2I/c (total reflection)
(8%)
3.Determine the inductance per unit length of a coaxial cable whose inner
conductor has a radian r1 and the outer conductor has a radian r2,shown as
Fig.1.The conductors are thin and carry equal currents in oppisite directions.
(10%)
4.Using Loop Model to explain why the diamagnetic material is repelled from
a region of greater magnetic field toward a region of lesser field in non-uniform
field.(Hint:drawings are necessary for the answer of this problem)(8%)
5.The formula of maximum fringes of a grating is given by dsin(theta)=m(lambda)
,where lambda is the wavelength of the light,integer m represents the order number
,grating spacing d and theta are measured as shown in Fig.2.Prove the
dispersion and resolving power of this grating are D=m/dcos(theta) and R=Nm(N
is the number of rulings),respectively.(8%)
6.In Fig.3, a long straight wire carries a current i1=30A and a rectangular
loop carries current i2=20A.TAke the dimensions to be a=1cm,b=8cm,and L=20cm.
In unit-vector notation,what is thw net force on the loop due to i1?(8%)
7.In an oscillating LC circuit,L=25mH and C=2.89 miu F.At time t=0 the current
is 9.2mA,the chargeon the capacitor is 3.8 miu C,and thw capacitor is charging.
What are (a)the maximum charge on the capacitor,and (b)the maximum current?
(c)If the charge on the capacitor is given by q=Qcos(wt+fi),what is the
phase angle fi?(10%)
8.The fractional half-width delta(Wd) of a resonance curve, such as the ones
in Fig.4 is the width of the curve athalf the maximum value of I.(a)Show that
delta(Wd)/w=R*根号(3c/L),where w is the angular frequency at resonance.
(b)What happens to thw ratio delta(Wd)/w with an increases in R?(8%)
9.题目太难打，请看照片
10.A luminous point is moving at speed Vo toward a spherical mirror with
radius of curvature r,along the central axis of the mirror.Show that the image
of this point is moving at speed V1=-(r/2p-r)(r/2p-r)Vo,where p is the distance
of the luminous point from the mirror at any given time.(8%)
11.In the Fig.6,a broad beam of light of wavelength 420nm is incident at 90度
on a thin,wedge-shaped film with index of refraction 1.7.Transmission gives
10 bright and 9 dark fringes along the film's length.What is the left-to-right
change in film thickness?(8%)
12.In the Fig.7,two radio-frequency point sources S1 and S2,separated by
diatance d=1.8m,around the two sources in a plane containing them.How many
(a)maxima and(b)minima does it detect?(8%)
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第九题：