課程名稱︰普通物理學甲下
課程性質︰系上必修
課程教師︰張寶棣
開課學院：資工系
開課系所︰資工系
考試日期（年月日）︰96年6月22日10:20~13:20
考試時限（分鐘）：3小時
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.An intense point source of light radiates 1MW isotropically.The source is
located 1m above an infinite, perfectly reflecting plane.Determine the
force that act on the plane.(8%)
2.The electric field of an electromagnetic wave oscillates in the y direction
and the Poynting vector is given by S(x,t)=(100W/m^2)cos^2(10x-(3×10^9)t)i,
where x is in meters and t is in seconds,(a)What is the direction of propa-
gation of the wave?(b)Find the wavelength and the frequency.(c)Find the
electric and magnetic fields.(12%)
3.Two polarizing sheets have their transmission axes crossed and a third sheet
is inserted so that its transmission axis makes an angle θ with that of the
first sheet.Find the intensity of the transmitted light as a function of θ?
(5%)
4.A thin film having an index of refraction of 1.5 is surrounded by air.It is
illuminated normally by white light and is viewed by reflection.Analysis of
resulting reflect light show that wavelength 360, 450, and 600 nm are the
only missing wavelengths or near the visible portion of the spectrum. That
is, for these wavelengths, there is destructive interference.(a)What is the
thickness of the film? (b)What visible wavelengths are brightest in the re-
flected interference pattern? (c)If this film were rest on glass with an
index of refraction of 1.6, what wavelengths in the visible spectrum would
be missing from the reflected light? (15%)
5.(a)In a double slit experiment, what ratio of d to a causes diffraction to
eliminate the fourth bright side fringe? (b)What other bright fringes are
also eliminated? (10%)
6.(a)What is the angular separation of two stars if their images are barely
resolved by the Thaw refracting telescope at the Allegheny observatory in
Pittsburgh? The lens diameter is 76 cm and its focal length is 14m.Assume
λ=550 nm. (b)Find the distance between these barely resolved stars if
each of them is 10 light-year from Earth. (10%)
7.Construct a Lorentz diagram for which the A-frame moves forward to the
B-frame at 0.8 c.(Suggested scale 1.0 cm = 30×10^8 cm) Include the world
line of an observer at rest in the A-frame at the position XA=120×10^8m.
(a)Locate the event E1 on this world line for which tA=0 and the event E2
for which tA = 20 sec. (b) Find the B-times of events E1 and E2 the B-time
interval between these events. (c)Find the B-distance of events E1 and E2
and the B-distance between these events. (15%)
8.A spaceship leaves Earth traveling at 0.71c. A second spaceship leaves the
first at a speed at 0.87c with respect to the first. Calculate the speed of
the second ship with respect to Earth if it is fired.(a) in the same direc-
tion the first space ship is already moving, (b) directly backward toward
Earth. (10%)
9.In the old West, a marshal riding on a train traveling 50m/s sees a duel
between two men standing on the Earth 50 m apart parallel to the train.The
marshal's instruments indicate that in his reference frame the two men fired
simultaneously. (a)Which of the two men, the first one the train passes (A)
or the second (B) should be arrested for firing the shoot? That is, in the
gunfighter's frame of reference, who fired first? (b)How much earlier did he
fire? (10%)
10.A farm boy studying physics believes that he can fit a 13.0-m long pole
into a 10.0-m long barn if he runs fast enough, carrying the pole.Can he
do it? Explain in detail. (5%)
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