36. Three 1/2 μF capacitors are connected in series
as shown in the diagram above. The
capacitance of the combination is
(A) 0.1 μF
(B) 1 μF
(C) 2/3 μF
(D) ½ μF
(E) 1/6
μF
37. A hair dryer is rated as 1200 W, 120 V.
Its effective internal resistance is
(A) 0.1 Ω
(B)
10 Ω
(C) 12Ω
(D) 120 Ω
(E)
1440 Ω
38. A point charge +Q is inside an uncharged
conducting spherical shell that in turn is near
several isolated point charges, as shown above.
The electric field at point P inside the shell
depends on the magnitude of
(A) Q only
(B) the charge distribution on the sphere only
(C) Q and the charge distribution on the sphere
(D) all of the point charges
(E) all of the point charges and the charge
distribution on the sphere
39. In a certain region, the electric field along
the xaxis is given by
E = ax + b, where a = 40 V/m
2
and b = 4 V/m.
The potential difference between the origin
and x = 0.5 m is
(A) 36 V
(B) 7 V
(C) 3 V
(D) 10 V
(E) 16 V
Questions 4041
A particle of charge +e and mass m moves with
speed v perpendicular to a uniform magnetic field
B
directed into the page. The path of the particle is
a circle of radius
r
, as shown above.
40. Which of the following correctly gives the
direction of motion and the equation
relating
v
and
r
?
Dir
ection
Equation
(A) Clockwise
eBr = mv
(B) Clockwise
eBr = mv
2
(C) Counterclockwise
eBr = mv
(D) Counterclockwise
eBr = mv
2
(E) Counterclockwise
eBr
2
= mv
2
41. The period of revolution of the particle
is
(A) mr/eB
(B)
/
m eB
(C) 2πm/eB
(D)
2
/
m eB
π
(E)
2
/
mr eB
42.
A
20
μF parallelplate capacitor is fully charged to 30
V. The energy stored in the capacitor is most nearly
(A) 9 x 10
3
J
(B) 9 x 10
3
J
(C) 6 x 10
4
J
(D) 2 x 10
4
J
(E) 2 x 10
7
J
43. A potential difference V is maintained between
two large, parallel conducting plates. An
electron starts from rest on the surface of one
plate and accelerates toward the other. Its
speed as it reaches the second plate is
proportional to
(A) 1/V
(B)
V
1
(C)
V
(D) V
(E) V
2
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View Full Document44. A wire of radius
R
has a current I uniformly
distributed across its crosssectional area.
Ampere's law is used with a concentric
circular path of radius r, with
r < R,
to
calculate the magnitude of the magnetic
field
B
at a distance
r
from the center of the
wire.
Which of the following equations
results from a correct application of
Ampere's law to this situation?
(A) B(2πr) = μ
0
I
(B) B(2πr) = μ
0
I(r
2
/R
2
)
(C) B(2πr) = 0
(D) B(2πR) = μ
0
I
(E)
B(2πR) = μ
0
I(r
2
/R
2
)
Questions 4546
Particles of charge Q and 4Q are located on the
xaxis as shown in the figure above. Assume
the particles are isolated from all other charges.
45. Which of the following describes the direction
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 Spring '10
 Ramesh
 Physics, Capacitance, AP Physics, Magnetic Field, Electric charge

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