课程名称︰普通物理学甲下
课程性质︰必修
课程教师︰王名儒
开课学院：理学院
开课系所︰大气系 数学系
考试日期（年月日）︰4/26
考试时限（分钟）：120
试题 :
1.Find the electro-static pressure on a spherical bubble with radius r and
surface charge density
2.Find th electric energy stored in a parrallel-plate capacitor of area A and
separation distance d with a total charge +-Q.Show that the energy density i
s
0.5*epsilon_0*E^2
3. A 2.0 kW heater element from a dryer has a length of 80 cm. If a 10
cm section is removed, what power is used by the shortened element
at the operation voltage 220V?
4. Two isolated concentric conducting spherical shells have radii R1 and
R2, uniform charges Q1 and Q2, and negligible thickness. Find the
electric potential V(r), where V(r=inf) = 0
.
5. An initially uncharged capacitor C is fully charged by a device of
constant emf e connected in series with a resister R. Show that the
final energy stored in the capacitor is half of the energy supplied by
the emf device. Show that the energy dissipated by the resister is also
half the energy supplied by the emf device.
6. Describe the operation principle of a cyclotron. You need to draw a
schematic diagram and derive the formula for the accelerating period
of the charged particle.
7. What is the magnetic field at a perpendicular distance r from a long
straight wire carrying a current i? You should argue about the
magnetic field direction first.
8. A rod lies across frictionless rails in a uniform
magnetic field B, as shown in the figure on the
right. The rod moves to the right with speed v. In
order for the emf around the circuit to be zero,
find the magnetic field as a function of time t,
B(t).
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