# here is the review for the capacitor test

```Capacitor Test Review Part 1: movie review (a step down from Dan Fullerton) 

Capacitors https://www.youtube.com/watch?v=OYcmMC9m0Bc 25 minutes Equivalent capacitance https://www.youtube.com/watch?v=vKDEZfLupMM 13 minutes Part 2: Workbook pages for chapter 29. Especially sections (not pages) 


29.2 29.6 29.7 Part 3: Study the CH29 lecture on www.hollocker.com ‐ especially slide 63 to the end! Part 4: Understand and be able to use the following equations: sf
f 

V  Vf  Vi    Es ds    E  ds
si
Es  
(29.3)
i
dV
ds
(29.11)
Vloop   ( V )i  0
(29.14)
i
Q  C VC
(charge on a capacitor)
Ceq  C1  C2  C3  ...
 1

1
1
Ceq   

 
 C1 C2 C3

(parallel capacitors)
(29.18)
(29.21)
1
(series capacitors)
(29.23)
Additionally. Part 5: Specific problems as follow on the next page. and 1) The charge on the
plates is maintained
original separation,
charge on the plates
A) Q/2.
square plates of a parallel‐plate capacitor is Q. The potential across the
with constant voltage by a battery as they are pulled apart to twice their
which is small compared to the dimensions of the plates. The amount of
is now equal to
B) Q.
C) 4Q.
D) 2Q.
E) Q/4.
5) When two or more capacitors are connected in parallel across a potential difference
A) each capacitor carries the same amount of charge.
B) the equivalent capacitance of the combination is less than the capacitance of any of
the capacitors.
C) the potential difference across each capacitor is the same.
D) All of the above choices are correct.
E) None of the above choices are correct.
7) In the circuit shown in the figure, the capacitors are
initially uncharged. The switch is first thrown to position
A and kept there for a long time. It is then thrown to
position B. Let the charges on the capacitors be Q1, Q2,
and Q3 and the potential differences across them be V1, V2,
and V3. Which of the following conditions must be true with
the switch in position B?
A) V1 + V2 = V3
B) V3 = V0
C) Q1 = Q2 = Q3
D) Q1 + Q2 = Q3
E) V1 = V2 = V3
8) An ideal parallel‐plate capacitor consists of a set of two parallel plates of area A
separated by a very small distance d. When this capacitor is connected to a battery that
maintains a constant potential difference between the plates, the energy stored in the capacitor
is U0. If the separation between the plates is doubled, how much energy is stored in the
capacitor?
A) U0/4
B) U0
C) U0/2
D) 2U0
E) 4U0
13) A charged capacitor stores energy U. Without connecting this capacitor to anything,
dielectric having dielectric constant K is now inserted between the plates of the capacitor,
completely filling the space between them. How much energy does the capacitor now store?
A) U
B) U / K
C) KU
D) 2KU
E) U / 2K
19) Three capacitors are connected as shown in
the figure. What is the equivalent capacitance
between points a and b?
A) 4.0 μF
B) 8.0 μF
C) 12 μF
D) 7.1 μF
E) 1.7 μF
37) The capacitive network shown in the figure is assembled with initially uncharged capacitors.
A potential difference, Vab = +100V, is applied across the network. The switch S in the network is
kept open. Assume that all the capacitances shown are accurate to two significant figures. What
is the total energy stored in the seven capacitors?
A) 72 mJ
B) 120 mJ
C) 144 mJ
D) 96 mJ
E) 48 mJ
D) 64 V.
E) 6.0 V.
25) Five capacitors are connected across
a potential difference Vab as shown in
the figure. Because of the dielectrics
used, each capacitor will break down if
the potential across it exceeds 30.0 V.
The largest that Vab can be without
damaging any of the capacitors is
closest to
A) 30 V.
B) 580 V.
C) 150 V.
41) A parallel-plate capacitor has a capacitance of 10 mF and is charged with a 20-V power supply.
The power supply is then removed and a dielectric material of dielectric constant 4.0 is used to
fill the space between the plates. What is the voltage now across the capacitor?
A) 5.0 V
B) 2.5 V
C) 80 V
D) 10 V
E) 20 V
33) A 6.00-μF parallel-plate capacitor has charges of ±40.0 μC on its plates. How much
potential energy is stored in this capacitor?
A) 113 μJ
B) 133 μJ
C) 103 μJ
D) 143 μJ
E) 123 μJ
```