課程名稱︰普通物理學甲下
課程性質︰化學系必帶,地質系選修
課程教師︰蔡政達
開課學院：理學院
開課系所︰物理系
考試日期（年月日）︰2010.06.22
考試時限（分鐘）：120 mins
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.
A parallel-plate capacitor with circular plates of radius R is being charged
as in Fig A
(a)Derive an expression for the magnetic field at radius r for the case r≦R
(8 points)
(b)Evaluate the field magnitude B for r=R/5=10 mm and dE/dt=1.00*10^12V/ms
(4 points)
(c)Derive an expression for the induced magnetic field for the case R≦r
(8 points)
│+-│
├→┤
│+-│
├→┤
i│+-│ i
→├→┤→
│+-│
├→┤
│+-│
├→┤
│+-│
├→┤
│+ │
_____
╱ ╲
╱ B ╲
∕ → ﹨
∕ ﹨
∣ ∣
∣ B↑ ↓B ∣
﹨ ∕
﹨ ← ∕
╲ B ╱
╲______╱
2.
A silt of width a is illuminated by white light.
(a)For what value of a will the first minimum for red light of wavelength
λ=600 nm appear at θ=30 degrees? (10 points)
(b)What is the wavelength λ' of the light whose first side different maximum
is 30 degrees, thus coinciding with the first minimum for the red light?
(10 degrees)
3.
An eraser of height 1.0 cm is placed 10.0 cm in front of a two-lens system.
Lens 1 (nearer the eraser) has focus length f1=-15cm, lens 2 has f2=12cm,
and the lens separation is d=12cm. For the image produced by lens 2, what are
(a)the image distance i2 (including sign),(5 points)
(b)the image height,(5 points)
(c)the image type (real or virtual),(5 points) and
(d)the image orientation (inverted relative to the eraser or not inverted)?
(5 points)
4.
In Fig B, two isotropic point sources of light (S1 and S2) are separated by
distance 3.0 um along a y axis and emit in phase at wavelength 1200 nm and
the same amplitude. A light detrctor is located at going P at coordinate Xp
on x axis
(1)What is the greatest value of Xp at which the detected light is minimum
due to destructive interference?(10 points)
(2)When P is very far away (x~∞), what are the phase different (in terms of
wavelengths) between waves arriving S1 and S2?(5 points),and the type of
interference they produce (approximately fully constructive or destructive?)
(5 points)
y
│
S1│ P
────●─────●──x
│
│
│
●S2
│
│
5
In a photoelectric experiment using a sodium surface, you find a stopping
potential of 1.85 V for a wavelength of 300 nm and a stopping potential of
0.820 V for a wavelength of 400 nm .From these data find
(a)a value for Planck constant (7 points)
(b)the work function Φ for sodium (7 points)
(c)the cutoff wavelength λ0 for sodium (6 points)
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