推 whaleswin16 :農化系已收精華區 04/28 02:10
課程名稱︰普通物理學乙
課程性質︰
課程教師︰王建萬
開課學院：
開課系所︰農化系
考試日期（年月日）︰2011.4.27
考試時限（分鐘）：110分
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
題末附:第九版<章節-題號>
1. A parallel-plate capacitor has plates of area 0.12m^2 and a seperation of
1.44cm. A battery charges the plates to a potential difference of 160V and is
then disconnected. A dielectric slab of thickness 4.8mm and dielectric
constant 3.6 is then placed symmetrically between the plates. (a) What is the
capacitance before the slab is inserted? (b) What is the capacitance with the
slab in place? What is the free charge q (c) before and (d) after the slab is
inserted? What is the magnitude of the electric field (e) in the place between
the plates and dielectric and (f) in the dielectric itself? (g) With the slab
in the place, what is the potential difference across the plates? (h) How much
external work involved in inserting the slab? (15%)
<25-53>
2.Two isolated, concentric, conducting spherical shells have radii R1=0.400m
and R2=1.00m, uniform charges q1=+4.00μC and q2=+2.00μC, and negligible
thicknesses.What is the magnitude of the electric field E at radial
distance (a) r=4.00m, (b) r=0.700m, and (c) r=0.200m? With V=0 at infinity,
what is V at (d) r=4.00m, (e) r=1.00m, (f) r=0.700m, (g) r=0.500m, (h) r=0.200m,
and (i)r=0? (15%)
<24-66>
3.What is the current in a wire of radius R=3.60mm if the magnitude of the
current density is given by (a) Ja=Jo (r/R)^2 and (b) Jb=Jo(1-r/R)^2, in which r is
the radial distance and Jo=5.50×10^4 A/m^2? (c) Which function maximizes the
current density near the wire's surface? (9%)
<26-11>
4.An electron follows a heilcal path in a uniform magnetic field given by
B = (30i-50j-30k)mT. At time t = 0, the electron's velocity is given by
v = (30i-30j+50k)m/s. (a) What is the angel ψ between v and B? The
electron's velocity changes with time. Do (b) its speed and(c)the angel ψ
change with time? (d) What is the radius of the helocal path?(e)what is
the pitch of the helical motion? (10%)
[electron mass m=9.11x10^-31kg, electron charge q=-e=-1.60x10^-19C]
<28-34>
5.Fig.1 shows a proton(p) on the central axis through a disk with a uniform
charge density due to excess electrons.Three of those electrons are shown:
electron ec at the disk center and electron es at opposite sides of the disk,
at radius R from the center.The proton is initially at distancez=R=2.50cm
from the disk.At that location, what are the magnitudes of(a)the electric
field Ec due to ec and (b)the net electric field Es,net due ti the electrons
es? The proton is then moved to z=R/12.0. What then are the magnitudes of (c)
Ec and (d)Es,net at the proton's location? (e)From (a) and (c) we see that
as the proton gets nearer to the disk, the magnitude of Ec increases. Why
does the magnitude of Es,net decrease, as we see from (b) and (d)? (10%)
<22-13>
6.In Fig.1, a solid sphere of radius a=3.00cm is concentric with a spherical
conducting shell of inner radius b=2.00a and outer radius of c=2.40a.
The sphere has a net uniform charge q1=+8.00fC; the shell has a net charge
q2=-q1. What is the magnitude of the electric field at radial distances
(a) r=0, (b)r=a/2.00, (c) r=a, (d) r=1.50a, (e) r=2.30a, and (f) r=3.50a?
What is the net charge on the (g) inner and (h) outer surface of the shell?
(14%) <23-49>
7.In the circuit of Fig.3, ε=1.6kV, C=8.5μF,R1=R2=R3=0.73MΩ.With C
completely uncharged, switch S is suddenly closed at t=0. At t=0, what are
(a)current i1 in resistor 1,(b)current i2 in resistor 2, and (c)current i3
in resistor 3? At t=∞, what are (d)i1,(e)i2,and (f)i3?What is the
potential difference V across resistor 2 at (g)t=0 (h)t=∞? (15%)
<27-63>
8. Fig.4 is a section of a conducting rod of radius R1 = 1.50mm and length
L =14.00m inside a thin-walled coaxial conducting cylindrical shell of
radius R2 = 10.00R1 and the same length L. The net charge on the rod is
Q1=+3.80x10^-12C; that on the shell is Q2=-2.00Q1.What are the(a) magnitude
E and (b) direction (radially inward or outward) of the electric field at
radial distance r = 2.00R2? What are (c) E and (d) direction at r = 5.00R1?
What is the charge on the(e) interior and (f) exterior surface of the
shell? (12%) <23-29>
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.112.228.101