Conceptual Physics

much potential energy is stored in the capacitor?

J

4.3 How much potential energy is stored in a 2.10eí6 F capacitor charged by a potential difference of 651 V?

J

4.4 A warning label on a 56.1 μF capacitor says that the capacitor can safely hold no more than 5.00 J of energy. What is the

maximum potential difference you can safely apply to the capacitor?

V

4.5 A capacitor that initially holds a charge of 3.31×10í^3 C on its plates fully discharges, in the process doing 5.50 J of work.

What is its capacitance?

F

4.6 A 79.1 μF capacitor is initially uncharged. After you expend 263 J of energy to charge it up, how much charge does it hold on

each plate?

C

4.7 A 6.40 nF capacitor is initially charged by a potential difference of 1.40×10^3 V. Later, the potential difference is increased so

that 5.10 μC of charge are added. What is the final electric potential energy stored in the capacitor?

J

Section 6 - Physics in medicine: defibrillator

6.1 A certain defibrillator sends 0.12 C of charge through the heart. The capacitor responsible for holding this charge before it is

released has a capacitance of 95 μF. How much energy is released when it discharges?

J

Section 8 - Dielectrics

8.1 The dielectric paste used in a tiny 360 nF capacitor has a dielectric constant of 50. What would the capacitor's capacitance

be without the dielectric?

nF

8.2 An isolated parallel-plate capacitor with no dielectric has an electric field of 8.4×10^3 V/m. When you inject dielectric paste

from an unlabeled jar, the field goes down to 1.4×10^3 V/m (the charges on the plates of the capacitor stay the same). What is

the dielectric constant of the unlabeled paste?

8.3 A tiny capacitor found in a clock radio uses a dielectric with a dielectric constant of 262. The electric field strength between

the "plates" of this capacitor is 6.11×10^5 V/m. If the dielectric were replaced with a vacuum, what would the strength of this

electric field become, assuming the charges on the plates remain the same?

V/m

8.4 When you insert a sheet of wood (ț = 2.00) between the plates of a capacitor, the capacitance becomes 22.0 nF. What

capacitance will it have if you insert a block of glass (ț = 6.00) instead?

nF

Section 11 - Physics at work: commercial capacitors

11.1 A variable capacitor has a range of capacitances from 2.0 nF to 20 nF. What is the difference between the most and least

charge that can be stored on the variable capacitor when it is connected to a 9.0 V source of potential difference?

C

(^488) Copyright 2007 Kinetic Books Co. Chapter 26 Problems