Download Homework7

Name: ______________________
WEEK 7 Homework
DUE ON Thursday 11/13/08
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1.
(1 point)
A proton (+1.6 × 10−19 C) moves 10 cm along the direction of an electric field of strength 3.0
N/C. The electrical potential difference between the proton's initial and ending points is:
a. 4.8 × 10−19 V.
b. 0.30 V.
c. 0.033 V.
d. 30 V.
____
2.
(2 points)
____
3.
(2 points)
An electron is released from rest at the negative plate of a parallel-plate capacitor. If the
distance across the plate is 5.0 mm and the potential difference across the plate is 5.0 V, with what
velocity does the electron hit the positive plate? (me = 9.1 × 10−31 kg, e = 1.6 × 10−19 C)
a. 2.6 × 105 m/s
b. 5.3 × 106 m/s
c. 1.0 × 106 m/s
d. 1.3 × 106 m/s
An electron with velocity v = 1.0 × 106 m/s is sent between the plates of a capacitor where the
electric field is E = 500 V/m. If the distance the electron travels through the field is 1.0 cm, how far is
it deviated (Y) in its path when it emerges from the electric field? (me = 9.1 × 10−31 kg, e = 1.6 × 10−19
C)
a.
b.
c.
d.
____
4.
2.2 mm
4.4 mm
2.2 cm
4.4 cm
(1 point)
Find the electrical potential at 0.15 m from a point charge of 6.0 µC. (ke = 8.99 × 109
N⋅m2/C2)
a.
b.
c.
d.
5.4 × 104 V
3.6 × 105 V
2.4 × 106 V
1.2 × 107 V
1
____
5.
(1 point)
Two point charges of values +3.4 and +6.6 µC are separated by 0.10 m. What is the electrical
potential at the point midway between the two point charges? (ke = 8.99 × 109 N⋅m2/C2)
a. +1.8 × 106 V
b. −0.90 × 106 V
c. +0.90 × 106 V
d. +3.6 × 106 V
____
6.
(1 point)
____
7.
(1 point)
____
8.
(1 point)
____
9.
(1 point)
A parallel-plate capacitor has a capacitance of 20 µF. What potential difference across the
plates is required to store 7.2 × 10−4 C on this capacitor?
a. 36 V
b. 2.2 × 10-2 V
c. 1.4 × 10−8 V
d. 68 V
Three capacitors of 1.0, 1.5, and 2.0 µF are connected in series. Find the combined
capacitance.
a. 4.5 µF
b. 4.0 µF
c. 2.2 µF
d. 0.46 µF
Two capacitors with capacitances of 1.5 and 0.25 µF, respectively, are connected in parallel.
The system is connected to a 50-V battery. What charge accumulates on the 1.5-µF capacitor?
a. 100 µC
b.
75 µC
c.
50 µC
d.
33 µC
a.
b.
c.
d.
What is the equivalent capacitance between points a and b? All capacitors are 1.0 µF.
4.0 µF
1 7 µF
0.60 µF
0.25 µF
2
____
10.
(1 point)
a.
b.
c.
d.
____
11.
____
12.
36 µF
32 µF
28 µF
24 µF
(1 point)
a.
b.
c.
d.
What is the equivalent capacitance of the combination shown?
29 µF
10 µF
40 µF
25 µF
(1 point)
a.
b.
c.
d.
If C = 36 µF, determine the equivalent capacitance for the combination shown.
What is the equivalent capacitance of the combination shown?
24 µF
100 µF
12 µF
4.6 µF
3
____
13.
(1 point)
A 0.25-µF capacitor is connected to a 400-V battery. What potential energy is stored in the
capacitor?
a. 1.2 × 10−12 J
b. 1.0 × 10−4 J
c. 0.040 J
d. 0.020 J
____
14.
(2 points)
____
15.
(1 point)
____
16.
(1 point)
____
17.
(1 point)
Two capacitors with capacitances of 1.0 µF and 0.50 µF, respectively, are connected in
series. The system is connected to a 100-V battery. What electrical potential energy is stored in the
1.0-µF capacitor?
a. 0.065 × 10−3 J
b. 4.3 × 10−3 J
c. 0.80 × 10−3 J
d. 5.6 × 10−4 J
Inserting a dielectric material between two charged parallel conducting plates, originally
separated by air and disconnected from a battery, will produce what effect on the capacitor?
a. increase charge
b. increase voltage
c. increase capacitance
d. decrease capacitance
A "sandwich" is constructed of two flat pieces of metal (2.00 cm on a side) with a
2.00-mm-thick piece of a dielectric called Rutile (κ = 100) in between them. What is the capacitance?
(ε0 = 8.85 × 10−12 C2/N⋅m2)
a. 177 pF
b. 885 nF
c. 8.85 µF
d. 100 µF
Two parallel-plate capacitors have the same plate area, and the gap between the plates is filled
with a dielectric with a dielectric constant equal to 4. The gap in capacitor A is one half that in
Capacitor B. What is the ratio of the capacitance of A to B?
a. 2
b. 1
c. 1/2
d. The ratio is not given.
4