الفيزياء العامة الجزء الثاني#موقع الفيزياء.كوم

Capacitors and capacitance
6.7 Problems
6.1) Two capacitors, C 1 =2µF and
C 2 =16µF, are connected in parallel.
What is the value of the equivalent
capacitance of the combination?
6.2) Calculate the equivalent
capacitance of the two capacitors in
the previous exercise if they are
connected in series.
6.3) A 100pF capacitor is charged to
a potential difference of 50V, the
charging battery then being
disconnected. The capacitor is then
connected in parallel with a second
(initially uncharged) capacitor. If
the measured potential difference
drops to 35V, what is the
capacitance of this second
capacitor?
6.4) A parallel-plate capacitor has
circular plates of 8.0cm radius and
1.0mm separation. What charge
will appear on the plates if a
potential difference of 100V is
applied?
6.5) In figure 6.18 the battery
supplies 12V. (a) Find the charge
on each capacitor when switch S 1 is
closed, and (b) when later switch S 2
is also closed. Assume C 1 =1µF,
C 2 =2µF, C 3 =3µF, and C 4 =4µF.
Figure 6.18
6.6) A parallel plate capacitor has a
plate of area A and separation d,
and is charged to a potential
difference V. The charging battery
is then disconnected and the plates
are pulled apart until their
separation is 2d. Derive expression
in term of A, d, and V for, the new
potential difference, the initial and
final stored energy, and the work
required to separate the plates.
6.7) A 6.0µF capacitor is connected
in series with a 4.0µF capacitor and
a potential difference of 200 V is
applied across the pair. (a) What is
the charge on each capacitor? (b)
What is the potential difference
across each capacitor?
6.8) Repeat the previous problem
for the same two capacitors
connected in parallel.
6.9) Show that the plates of a
parallel-plate capacitor attract each
other with a force given by
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