Objective Questions
1. True or False? (a) From the definition of capacitance C = Q / F0
4 4
V, it follows that an uncharged
capacitor has a capacitance of zero. (b) As described by the definition of capacitance, the
potential difference across an uncharged capacitor is zero.
2. By what factor is the capacitance of a metal sphere multiplied if its volume is tripled? (a) 3
(b) 31/3 (c) 1 (d) 3–1/3 (e)
3. An electronics technician wishes to construct a parallel plate capacitor using rutile ( = 100) as
the dielectric. The area of the plates is 1.00 cm2. What is the capacitance if the rutile thickness is
1.00 mm? (a) 88.5 pF (b) 177 pF (c) 8.85 F 0
6 D
F (d) 100 F 0
6 D
F (e) 35.4 F 0
6 D
F
4. A capacitor with very large capacitance is in series with another capacitor with very small
capacitance. What is the equivalent capacitance of the combination? (a) slightly greater than the
capacitance of the large capacitor (b) slightly less than the capacitance of the large capacitor
(c) slightly greater than the capacitance of the small capacitor (d) slightly less than the
capacitance of the small capacitor
5. If three unequal capacitors, initially uncharged, are connected in series across a battery, which of
the following statements is true? (a) The equivalent capacitance is greater than any of the
individual capacitances. (b) The largest voltage appears across the smallest capacitance. (c) The
largest voltage appears across the largest capacitance. (d) The capacitor with the largest
capacitance has the greatest charge. (e) The capacitor with the smallest capacitance has the
smallest charge.
6. (i) Rank the following five capacitors from greatest to smallest capacitance, noting any cases of
equality. (a) a 20- F 0
6 D
F capacitor with a 4-V potential difference between its plates (b) a 30- F 0
6 D
F
capacitor with charges of magnitude 90 F 0
6 D
C on each plate (c) a capacitor with charges of
magnitude 80 F 0
6 D
C on its plates, differing by 2 V in potential, (d) a 10- F 0
6 D
F capacitor storing
energy 125 F 0
6 D
J (e) a capacitor storing energy 250 F 0
6 D
J with a 10-V potential difference (ii) Rank
the same capacitors in part (i) from largest to smallest according to the potential difference
between the plates. (iii) Rank the capacitors in part (i) in the order of the magnitudes of the
charges on their plates. (iv) Rank the capacitors in part (i) in the order of the energy they store.
7. (i) What happens to the magnitude of the charge on each plate of a capacitor if the potential
difference between the conductors is doubled? (a) It becomes four times larger. (b) It becomes
two times larger. (c) It is unchanged. (d) It becomes one-half as large. (e) It becomes one-fourth
as large. (ii) If the potential difference across a capacitor is doubled, what happens to the energy
stored? Choose from the same possibilities as in part (i).
8. A parallel-plate capacitor is connected to a battery. What happens to the stored energy if the plate
separation is doubled while the capacitor remains connected to the battery? (a) It remains the
same. (b) It is doubled. (c) It decreases by a factor of 2. (d) It decreases by a factor of 4. (e) It
increases by a factor of 4.
hapter 26
26_c26_p740-770
