Ch 25
14 Two conducting spheres are very far
apart. The smaller sphere carries a
total charge of 6 micro-C. The larger
sphere has a radius twice that of the
smaller sphere and is neutral. After
the two spheres are connected by a
thin conducting wire, the charges on
the smaller and the larger spheres,
respectively are:
A1 2 micro-C
A2 -4 micro-C
A3 3 micro-C
A4 0
A5 -6 micro-C
and
and
and
and
and
4
10
3
6
12
micro-C.
micro-C.
micro-C.
micro-C.
micro-C.
15 Find the WRONG statement:
When a dielectric materials is
inserted between the plates of an
isolated capacitor, it will provide
the following advantages:
A1 Increase the original charge on
the conducting plates.
A2 Increase the maximum energy that
can be stored in the capacitor.
A3 Increase the capacitance of the
capacitor.
A4 Increase the maximum operating
voltage of the capacitor.
A5 Mechanical support between the
conducting plates.
16 Consider the combination of
capacitors in Fig. (3). The energy
stored in the 5 micro-F capacitor is
0.20 J. The energy stored in 4 micro-F
capacitor is:
A1
A2
A3
A4
A5
0.16
0.20
0.36
0.40
0.04
J.
J.
J.
J.
J.
17 An isolated capacitor, C1 = 20.0
micro-F has a potential difference of
26.0 V. When an uncharged capacitor
C2, of unknown value, is connected
across C1, the potential difference
becomes 16.0 V for both. What is the
value of C2?
A1
A2
A3
A4
A5
12.5*10**(-6)
25.0*10**(-6)
20.0*10**(-6)
1.00*10**(-6)
10.2*10**(-6)
F.
F.
F.
F.
F.
18 A parallel plate capacitor of
capacitance C has a charge of
magnitude q when connected to a
battery of potential difference V.
After being fully charged, the
capacitor is disconnected from the
battery and the separation between the
plates is doubled.
Which one of the following statements
is TRUE?
A1 The voltage across the plates
doubles.
A2 The voltage across the plates is
halved.
A3 The capacitor's capacitance
doubles.
A4 The magnitude of the charge on
the plates doubles.
A5 The magnitude of the charge on
the plates is halved.
Chapters 25 (021)
A parallel plate capacitor has a plate area of 0.2 m**2
and a plate separation of 0.1 mm. The charge on each
plate is 4.0 microCoulombs. What is the electric field
between the plates?
A1
A2
A3
A4
A5
2.3*10**6 V/m
4.0*10**2 V/m
1.0*10**6 V/m
4.0*10**12 V/m
zero
The potential difference between the plates of an
isolated, charged capacitor is Vo. A slab of dielectric
material is inserted filling completely the space between
the plates. The potential difference across the capacitor is
now Vo/2. Find the dielectric constant of the material.
A1
A2
A3
A4
A5
2
0.5
8
4
16
Figure 5 shows six capacitors each having a capacitance
of 6-microFarad.The capacitance between points a and b
is:
A1
A2
A3
A4
A5
4 microFarad
3 microFarad
6 microFarad
9 microFarad
1 microFarad
In figure 6: V = 100 V, C1 = 10.0, C2 = 5.00, C3 = 4.00.
All capacitor values are in microFarads. What is the
energy stored in C1?
A1
A2
A3
A4
A5
5.56 mJ
1.12 mJ
11.2 mJ
50.0 mJ
10.3 mJ
S-26-6
By what factor does the capacitance of a metal sphere
increase if its volume is tripled?
S-26-28
Two capacitors when connected in parallel give an equivalent
capacitance of 9.0 pF, and an equivalent capacitance of 2.0 pF
when connected in series. What is the capacitance of the two
capacitors?
S-26-31
Four capacitors are connected as shown in the figure. Find the
equivalent capacitance between points [a] and [b]. Calculate the
charge on each capacitor if Vab = 15 volts.
15 F 3 F
20 F
a
b
6.0 F
S-26-49
A 16.0 pF parallel plate capacitor is charged by a 10 volt
battery. If each plate of the capacitor has an area of 5.00 cm2,
what is the energy stored in the capacitor? What is the energy
density?
If nylon (K= 3.4) is now inserted between the plates (with the
battery connected), find the energy stored in the capacitor.
Would it be any different if the battery were disconnected when
inserting the dielectric?