A capacitor of unknown capacitance C is charged to 100 V and connected across an

The two metal objects in Fig. 25-24 have net charges of 70 pC and 70 pC, which result in a 20 V potential difference between them. (a) What is the capacitance of the system? (b) If the charges are changed to 200 pC and 200 pC, what does the capacitance become? (c) What does the potential difference become? Figure 25-24 Problem 1.

The capacitor in Fig. 25-25 has a capacitance of 25 mF and is initially uncharged. The battery provides a potential difference of 120 V. After switch S is closed, how much charge will pass through it? C + S

A parallel-plate capacitor has circular plates of 8.20 cm radius and 1.30 mm separation. (a) Calculate the capacitance. (b) Find the charge for a potential difference of 120 V.

The plates of a spherical capacitor have radii 38.0 mm and 40.0 mm. (a) Calculate the capacitance. (b) What must be the plate area of a parallel-plate capacitor with the same plate separation and capacitance?

What is the capacitance of a drop that results when two mercury spheres, each of radius R 2.00 mm, merge?

You have two flat metal plates, each of area 1.00 m2 , with which to construct a parallel-plate capacitor. (a) If the capacitance of the device is to be 1.00 F, what must be the separation between the plates? (b) Could this capacitor actually be constructed?

If an uncharged parallel-plate capacitor (capacitance C) is connected to a battery, one plate becomes negatively charged as electrons move to the plate face (area A). In Fig. 25-26, the depth d from which the electrons come in the plate in a particular capacitor is plotted against a range of values for the potential difference V of the battery. The density of conduction electrons in the copper plates is 8.49  1028 electrons/m3. The vertical scale is set by ds 1.00 pm, and the horizontal scale is set by Vs 20.0 V. What is the ratio C/A? d (pm) Vs V (V) 0 Figure 25-26 Problem 7.

How many 1.00 mF capacitors must be connected in parallel to store a charge of 1.00 C with a potential of 110 V across the capacitors?

Each of the uncharged capacitors in Fig. 25-27 has a capacitance of 25.0 mF. A potential difference of V 4200 V is established when the switch is closed. How many coulombs of charge then pass through meter A? A C C C Figure 25-27 Problem 9.

In Fig. 25-28, find the equivalent capacitance of the combination. Assume that C1 is 10.0 mF, C2 is 5.00 mF, and C3 is 4.00 mF. Figure 25-28 Problems 10 and 34. V

In Fig. 25-29, find the equivalent capacitance of the combination. Assume that C1 10.0 mF, C2 5.00 mF, and C3 4.00 mF. V C2 C3 C1 Figure 25-29 Problems 11, 17, and 38.

Two parallel-plate capacitors, 6.0 mF each, are connected in parallel to a 10 V battery. One of the capacitors is then squeezed so that its plate separation is 50.0% of its initial value. Because of the squeezing, (a) how much additional charge is transferred to the capacitors by the battery and (b) what is the increase in the total charge stored on the capacitors?

A 100 pF capacitor is charged to a potential difference of 50 V, and the charging battery is disconnected. The capacitor is then connected in parallel with a second (initially uncharged) capacitor. If the potential difference across the first capacitor drops to 35 V, what is the capacitance of this second capacitor?

In Fig. 25-30, the battery has a potential difference of V 10.0 V and the five capacitors each have a capacitance of 10.0 mF. What is the charge on (a) capacitor 1 and (b) capacitor 2? C2 + V C1 Figure 25-30 Problem 14.

In Fig. 25-31, a 20.0 V battery is connected across capacitors of capacitances C1 C6 3.00 mF and C3 C5 2.00C2 2.00C4 4.00 mF. What are (a) the equivalent capacitance Ceq of the capacitors and (b) the charge stored by Ceq? What are (c) V1 and (d) q1 of capacitor 1, (e) V2 and (f) q2 of capacitor 2, and (g) V3 and (h) q3 of capacitor 3? V + C C2 5 C3 C4 C6 C1 Figure 25-31 Problem 15.

Plot 1 in Fig. 25-32a gives the charge q that can be stored on capacitor 1 versus the electric potential V set up across it. The vertical scale is set by qs 16.0 mC, and the horizontal scale is set by Vs 2.0 V. Plots 2 and 3 are similar plots for capacitors 2 and 3, respectively. Figure 25-32b shows a circuit with those three capacitors and a 6.0 V battery. What is the charge stored on capacitor 2 in that circuit? (a) (b) qs 0 1 V (V) Vs 2 q 3 ( C) C2 C3 C1 V Figure 25-32 Problem 16.

In Fig. 25-29, a potential difference of V 100.0 V is applied across a capacitor arrangement with capacitances C1 10.0 mF, C2 5.00 mF, and C3 4.00 mF. If capacitor 3 undergoes electrical breakdown so that it becomes equivalent to conducting wire, what is the increase in (a) the charge on capacitor 1 and (b) the potential difference across capacitor 1?

Figure 25-33 shows a circuit section of four air-filled capacitors that is connected to a larger circuit.The graph below the section shows the electric potential V(x) as a function of position x along the lower part of the section, through capacitor 4. Similarly, the graph above the section shows the electric potential V(x) as a function of position x along the upper part of the section, through capacitors 1, 2, and 3. Capacitor 3 has a capacitance of 0.80 mF. What are the capacitances of (a) capacitor 1 and (b) capacitor 2? 12 x x 4 1 2 3 Figure 25-33 Problem 18.

In Fig. 25-34, the battery has potential difference V 9.0 V, C2 3.0 mF, C4 4.0 mF, and all the capacitors are initially uncharged. When switch S is closed, a total charge of 12 mC passes through point a and a total charge of 8.0 mC passes through point b.What are (a) C1 and (b) C3? V S a b C1 C2 C3 C4 Figure 25-34 Problem 19.

Figure 25-35 shows a variable air gap capacitor for manual tuning. Alternate plates are connected together; one group of plates is fixed in position, and the other group is capable of rotation. Consider a capacitor of n 8 plates of alternating polarity, each plate having area A 1.25 cm2 and separated from adjacent plates by distance d 3.40 mm.What is the maximum capacitance of the device? A d A Figure 25-35 Problem 20.

In Fig. 25-36, the capacitances are C1 1.0 mF and C2 3.0 mF, and both capacitors are charged to a potential difference of V 100 V but with opposite polarity as shown. Switches S1 and S2 are now closed. (a) What is now the potential difference between points a and b? What now is the charge on capacitor (b) 1 and (c) 2? S2 S1 C1 C2 a Figure 25-36 Problem 21.

In Fig. 25-37, V 10 V, C1 10 mF, and C2 C3 20 mF. Switch S is first thrown to the left side until capacitor 1 reaches equilibrium. Then the switch is thrown to the right. When equilibrium is again reached, how much charge is on capacitor 1? S V C1 C2 C3 Figure 25-37 Problem 22.

The capacitors in Fig. 25-38 are initially uncharged. The capacitances are C1 4.0 mF, C2 8.0 mF, and C3 12 mF, and the batterys potential difference is V 12 V. When switch S is closed, how many electrons travel through (a) point a, (b) point b, (c) point c, and (d) point d? In the figure, do the electrons travel up or down through (e) point b and (f) point c? V a d b c S C2 C1 C3 Figure 25-38 Problem 23.

Figure 25-39 represents two air-filled cylindrical capacitors connected in series across a battery with potential V 10 V. Capacitor 1 has an inner plate radius of 5.0 mm, an outer plate radius of 1.5 cm, and a length of 5.0 cm. Capacitor 2 has an inner plate radius of 2.5 mm, an outer plate radius of 1.0 cm, and a length of 9.0 cm.The outer plate of capacitor 2 is a conducting organic membrane that can be stretched, and the capacitor can be inflated to increase the plate separation. If the outer plate radius is increased to 2.5 cm by inflation, (a) how many electrons move through point P and (b) do they move toward or away from the battery? Figure 25-39 Problem 24. C1 C2 V P

In Fig. 25-40, two parallel-plate capacitors (with air between the plates) are connected to a battery. Capacitor 1 has a plate area of 1.5 cm2 and an electric field (between its plates) of magnitude 2000 V/m. Capacitor 2 has a plate area of 0.70 cm2 and an electric field of magnitude 1500 V/m. What is the total charge on the two capacitors? C1 C2 Figure 25-40 Problem 25.

Capacitor 3 in Fig. 25-41a is a variable capacitor (its capacitance C3 can be varied). Figure 25-41b gives the electric potential V1 across capacitor 1 versus C3.The horizontal scale is set by C3s = 12.0 mF. Electric potential V1 approaches an asymptote of 10 V as C3 : . What are (a) the electric potential V across the battery, (b) C1, and (c) C2? V C2 C3 C1 10 8 6 4 2 0 C3 ( F) C3s Figure 25-41 Problem 26.

Figure 25-42 shows a 12.0 V battery and four uncharged capacitors of capacitances C1 1.00 mF, C2 2.00 mF,C3 3.00 mF,and C4 4.00 mF. If only switch S1 is closed, what is the charge on (a) capacitor 1, (b) capacitor 2, (c) capacitor 3, and (d) capacitor 4? If both switches are closed, what is the charge on (e) capacitor 1, (f) capacitor 2, (g) capacitor 3,and (h) capacitor 4? C1 C3 C2 C4 S1 B + Figure 25-42 Problem 27.

Figure 25-43 displays a 12.0 V battery and 3 uncharged capacitors of capacitances C1 4.00 mF, C2 6.00 mF, and C3 3.00 mF. The switch is thrown to the left side until capacitor 1 is fully charged. Then the switch is thrown to the right. What is the final charge on (a) capacitor 1, (b) capacitor 2, and (c) capacitor 3? C2 C3 C1 V0 +

What capacitance is required to store an energy of 10 kWh at a potential difference of 1000 V?

How much energy is stored in 1.00 m3 of air due to the fair weather electric field of magnitude 150 V/m?

A 2.0 mF capacitor and a 4.0 mF capacitor are connected in parallel across a 300 V potential difference. Calculate the total energy stored in the capacitors.

A parallel-plate air-filled capacitor having area 40 cm2 and plate spacing 1.0 mm is charged to a potential difference of 600 V. Find (a) the capacitance, (b) the magnitude of the charge on each plate, (c) the stored energy, (d) the electric field between the plates, and (e) the energy density between the plates.

A charged isolated metal sphere of diameter 10 cm has a potential of 8000 V relative to V 0 at infinity. Calculate the energy density in the electric field near the surface of the sphere.

In Fig. 25-28, a potential difference V 100 V is applied across a capacitor arrangement with capacitances C1 10.0 mF, C2 5.00 mF, and C3 4.00 mF. What are (a) charge q3, (b) potential difference V3, and (c) stored energy U3 for capacitor 3, (d) q1, (e) V1, and (f) U1 for capacitor 1, and (g) q2, (h) V2, and (i) U2 for capacitor 2? 3

Assume that a stationary electron is a point of charge. What is the energy density u of its electric field at radial distances (a) r 1.00 mm, (b) r 1.00 mm, (c) r 1.00 nm, and (d) r 1.00 pm? (e) What is u in the limit as r : 0? 3

As a safety engineer, you must evaluate the practice of storing flammable conducting liquids in nonconducting containers. The company supplying a certain liquid has been using a squat, cylindrical plastic container of radius r 0.20 m and filling it to height h 10 cm, which is not the containers full interior height (Fig. 25-44). Your investigation reveals that during handling at the company, the exterior surface of the container commonly acquires a negative charge density of magnitude 2.0 mC/m2 (approximately uniform). Because the liquid is a conducting material, the charge on the container induces charge separation within the liquid. (a) How much negative charge is induced in the center of the liquids bulk? (b) Assume the capacitance of the central portion of the liquid relative to ground is 35 pF. What is the potential energy associated with the negative charge in that effective capacitor? (c) If a spark occurs between the ground and the central portion of the liquid (through the venting port), the potential energy can be fed into the spark. The minimum spark energy needed to ignite the liquid is 10 mJ. In this situation, can a spark ignite the liquid? Venting port + + + + + + + + + + + + + h r Figure 25-44 Problem 36.

The parallel plates in a capacitor, with a plate area of 8.50 cm2 and an air-filled separation of 3.00 mm, are charged by a 6.00 V battery. They are then disconnected from the battery and pulled apart (without discharge) to a separation of 8.00 mm. Neglecting fringing, find (a) the potential difference between the plates, (b) the initial stored energy, (c) the final stored energy, and (d) the work required to separate the plates.

In Fig. 25-29, a potential difference V 100 V is applied across a capacitor arrangement with capacitances C1 10.0 mF, C2 5.00 mF, and C3 15.0 mF. What are (a) charge q3, (b) potential difference V3, and (c) stored energy U3 for capacitor 3, (d) q1, (e) V1, and (f) U1 for capacitor 1, and (g) q2, (h) V2, and (i) U2 for capacitor 2?

In Fig. 25-45, C1 10.0 mF, C2 20.0 mF, and C3 25.0 mF. If no capacitor can withstand a potential difference of more than 100 V without failure, what are (a) the magnitude of the maximum potential difference that can exist between points A and B and (b) the maximum energy that can be stored in the three-capacitor arrangement? A B C1 C2 C3 Figure 25-45 Problem 39.

An air-filled parallel-plate capacitor has a capacitance of 1.3 pF. The separation of the plates is doubled, and wax is inserted between them. The new capacitance is 2.6 pF. Find the dielectric constant of the wax.

A coaxial cable used in a transmission line has an inner radius of 0.10 mm and an outer radius of 0.60 mm. Calculate the capacitance per meter for the cable. Assume that the space between the conductors is filled with polystyrene.

A parallel-plate air-filled capacitor has a capacitance of 50 pF. (a) If each of its plates has an area of 0.35 m2 , what is the separation? (b) If the region between the plates is now filled with material having k 5.6, what is the capacitance?

Given a 7.4 pF air-filled capacitor, you are asked to convert it to a capacitor that can store up to 7.4 mJ with a maximum potential difference of 652 V. Which dielectric in Table 25-1 should you use to fill the gap in the capacitor if you do not allow for a margin of error?

You are asked to construct a capacitor having a capacitance near 1 nF and a breakdown potential in excess of 10 000 V. You think of using the sides of a tall Pyrex drinking glass as a dielectric, lining the inside and outside curved surfaces with aluminum foil to act as the plates. The glass is 15 cm tall with an inner radius of 3.6 cm and an outer radius of 3.8 cm. What are the (a) capacitance and (b) breakdown potential of this capacitor?

A certain parallel-plate capacitor is filled with a dielectric for which k 5.5. The area of each plate is 0.034 m2 , and the plates are separated by 2.0 mm.The capacitor will fail (short out and burn up) if the electric field between the plates exceeds 200 kN/C. What is the maximum energy that can be stored in the capacitor?

In Fig. 25-46, how much charge is stored on the parallel-plate capacitors by the 12.0 V battery? One is filled with air, and the other is filled with a dielectric for which k 3.00; both capacitors have a plate area of 5.00  103 m2 and a plate separation of 2.00 mm. C1 C2 Figure 25-46 Problem 46.

A certain substance has a dielectric constant of 2.8 and a dielectric strength of 18 MV/m. If it is used as the dielectric material in a parallel-plate capacitor, what minimum area should the plates of the capacitor have to obtain a capacitance of 7.0  102 mF and to ensure that the capacitor will be able to withstand a potential difference of 4.0 kV?

Figure 25-47 shows a parallelplate capacitor with a plate area A 5.56 cm2 and separation d 5.56 mm. The left half of the gap is filled with material of dielectric constant k1 7.00; the right half is filled with material of dielectric constant k2 12.0.What is the capacitance? /2 A/2 1 2 d Figure 25-47 Problem 48.

Figure 25-48 shows a parallel-plate capacitor with a plate area A 7.89 cm2 and plate separation d 4.62 mm. The top half of the gap is filled with material of dielectric constant k1 11.0; the bottom half is filled with material of dielectric constant k2 12.0. What is the capacitance? 1 Figure 25-48 Problem 49.

Figure 25-49 shows a parallelplate capacitor of plate area A 10.5 cm2 and plate separation 2d 7.12 mm. The left half of the gap is filled with material of dielectric constant k1 21.0; the top of the right half is filled with material of dielectric constant k2 42.0; the bottom of the right half is filled with material of dielectric constant k3 58.0.What is the capacitance? 2d d d 1 2 3 A/ Figure 25-49 Problem 50.

A parallel-plate capacitor has a capacitance of 100 pF, a plate area of 100 cm2 , and a mica dielectric (k 5.4) completely filling the space between the plates. At 50 V potential difference, calculate (a) the electric field magnitude E in the mica, (b) the magnitude of the free charge on the plates, and (c) the magnitude of the induced surface charge on the mica.

For the arrangement of Fig. 25-17, suppose that the battery remains connected while the dielectric slab is being introduced. Calculate (a) the capacitance, (b) the charge on the capacitor plates, (c) the electric field in the gap, and (d) the electric field in the slab, after the slab is in place.

A parallel-plate capacitor has plates of area 0.12 m2 and a separation of 1.2 cm. A battery charges the plates to a potential difference of 120 V and is then disconnected.A dielectric slab of thickness 4.0 mm and dielectric constant 4.8 is then placed symmetrically between the plates. (a) What is the capacitance before the slab is inserted? (b) What is the capacitance with the slab in place? What is the free charge q (c) before and (d) after the slab is inserted? What is the magnitude of the electric field (e) in the space between the plates and dielectric and (f) in the dielectric itself? (g) With the slab in place, what is the potential difference across the plates? (h) How much external work is involved in inserting the slab?

Two parallel plates of area 100 cm2 are given charges of equal magnitudes 8.9  107 C but opposite signs. The electric field within the dielectric material filling the space between the plates is 1.4  106 V/m. (a) Calculate the dielectric constant of the material. (b) Determine the magnitude of the charge induced on each dielectric surface.

The space between two concentric conducting spherical shells of radii b 1.70 cm and a 1.20 cm is filled with a substance of dielectric constant k 23.5. A potential difference V 73.0 V is applied across the inner and outer shells. Determine (a) the capacitance of the device, (b) the free charge q on the inner shell, and (c) the charge q induced along the surface of the inner shell. Ad

In Fig. 25-50, the battery potential difference V is 10.0 V and each of the seven capacitors has capacitance 10.0 mF. What is the charge on (a) capacitor 1 and (b) capacitor 2? C1 C2 V + Figure 25-50 Problem 56.

In Fig. 25-51, V 9.0 V, C1 C2 30 mF, and C3 C4 15 mF.What is the charge on capacitor 4? C3 C2 C1 C4 V Figure 25-51 Problem 57.

(a) If C 50 mF in Fig. 25-52, what is the equivalent capacitance between points A and B? (Hint: First imagine that a battery is connected between those two points.) (b) Repeat for points A and D. 2C 4C C 6C A Figure 25-52 Problem 58.

In Fig. 25-53, V 12 V, C1 C4 2.0 mF, C2 4.0 mF, and C3 1.0 mF. What is the charge on capacitor 4? C1 C3 C2 C4 V Figure 25-53 Problem 59.

The chocolate crumb mystery. This story begins with Problem 60 in Chapter 23. As part of the investigation of the biscuit factory explosion, the electric potentials of the workers were measured as they emptied sacks of chocolate crumb powder into the loading bin, stirring up a cloud of the powder around themselves. Each worker had an electric potential of about 7.0 kV relative to the ground, which was taken as zero potential. (a) Assuming that each worker was effectively a capacitor with a typical capacitance of 200 pF, find the energy stored in that effective capacitor. If a single spark between the worker and any conducting object connected to the ground neutralized the worker, that energy would be transferred to the spark. According to measurements, a spark that could ignite a cloud of chocolate crumb powder, and thus set off an explosion, had to have an energy of at least 150 mJ. (b) Could a spark from a worker have set off an explosion in the cloud of powder in the loading bin? (The story continues with Problem 60 in Chapter 26.)

Figure 25-54 shows capacitor 1 (C1 8.00 mF), capacitor 2 (C2 6.00 mF), and capacitor 3 (C3 8.00 mF) connected to a 12.0 V battery.When switch S is closed so as to connect uncharged capacitor 4 (C4 6.00 mF), (a) how much charge passes through point P from the battery and (b) how much charge shows up on capacitor 4? (c) Explain the discrepancy in those two results. P S C1 C3

Two air-filled, parallel-plate capacitors are to be connected to a 10 V battery, first individually, then in series, and then in parallel. In those arrangements, the energy stored in the capacitors turns out to be, listed least to greatest: 75 mJ, 100 mJ, 300 mJ, and 400 mJ. Of the two capacitors, what is the (a) smaller and (b) greater capacitance?

Two parallel-plate capacitors, 6.0 mF each, are connected in series to a 10 V battery. One of the capacitors is then squeezed so that its plate separation is halved. Because of the squeezing, (a) how much additional charge is transferred to the capacitors by the battery and (b) what is the increase in the total charge stored on the capacitors (the charge on the positive plate of one capacitor plus the charge on the positive plate of the other capacitor)?

n Fig. 25-55, V 12 V, C1 C5 C6 6.0 mF, and C2 C3 C4 4.0 mF. What are (a) the net charge stored on the capacitors and (b) the charge on capacitor 4? C1 C4 C5 C3 C6 V Figure 25-55 Problem 64.

In Fig. 25-56, the parallel-plate capacitor of plate area 2.00 102 m2 is filled with two dielectric slabs, each with thickness 2.00 mm. One slab has dielectric constant 3.00, and the other, 4.00. How much charge does the 7.00 V battery store on the capacitor? Figure 25-56 Problem 65. V

A cylindrical capacitor has radii a and b as in Fig. 25-6. Show that half the stored electric potential energy lies within a cylinder whose radius is r 1ab.

A capacitor of capacitance C1 6.00 mF is connected in series with a capacitor of capacitance C2 4.00 mF, and a potential difference of 200 V is applied across the pair. (a) Calculate the equivalent capacitance. What are (b) charge q1 and (c) potential difference V1 on capacitor 1 and (d) q2 and (e) V2 on capacitor 2? 68

Repeat Problem 67 for the same two capacitors but with them now connected in parallel.

A certain capacitor is charged to a potential difference V. If you wish to increase its stored energy by 10%, by what percentage should you increase V?

A slab of copper of thickness b 2.00 mm is thrust into a parallelplate capacitor of plate area A 2.40 cm2 and plate separation d 5.00 mm, as shown in Fig. 25-57; the slab is exactly halfway between the plates. (a) What is the capacitance after the slab is introduced? (b) If a charge q 3.40 mC is maintained on the plates, what is the ratio of the stored energy before to that after the slab is inserted? (c) How much work is done on the slab as it is inserted? (d) Is the slab sucked in or must it be pushed in? b d Figure 25-57 Problems 70 and 71.

Repeat Problem 70, assuming that a potential difference V 85.0 V, rather than the charge, is held constant. b d Figure 25-57 Problems 70 and 71.

A potential difference of 300 V is applied to a series connection of two capacitors of capacitances C1 2.00 mF and C2 8.00 mF. What are (a) charge q1 and (b) potential difference V1 on capacitor 1 and (c) q2 and (d) V2 on capacitor 2? The charged capacitors are then disconnected from each other and from the battery. Then the capacitors are reconnected with plates of the same signs wired together (the battery is not used). What now are (e) q1, (f) V1, (g) q2, and (h) V2? Suppose, instead, the capacitors charged in part (a) are reconnected with plates of opposite signs wired together.What now are (i) q1, (j) V1, (k) q2, and (l) V2? 7

Figure 25-58 shows a fourcapacitor arrangement that is connected to a larger circuit at points A and B. The capacitances are C1 10 mF and C2 C3 C4 20 mF. The charge on capacitor 1 is 30 mC. What is the magnitude of the potential difference VA  VB? C4 B C2 C1

You have two plates of copper, a sheet of mica (thickness 0.10 mm, k 5.4), a sheet of glass (thickness 2.0 mm, k 7.0), and a slab of paraffin (thickness 1.0 cm, k 2.0). To make a parallel-plate capacitor with the largest C, which sheet should you place between the copper plates? 75 A

A capacitor of unknown capacitance C is charged to 100 V and connected across an initially uncharged 60 mF capacitor. If the final potential difference across the 60 mF capacitor is 40 V, what is C?

A 10 V battery is connected to a series of n capacitors, each of capacitance 2.0 mF. If the total stored energy is 25 mJ, what is n?

In Fig. 25-59, two parallelplate capacitors A and B are connected in parallel across a 600 V battery. Each plate has area 80.0 cm2 ; the plate separations are 3.00 mm. Capacitor A is filled with air; capacitor B is filled with a dielectric of dielectric constant k 2.60. Find the magnitude of the electric field within (a) the dielectric of capacitor B and (b) the air of capacitor A. What are the free charge densities s on the higher-potential plate of (c) capacitor A and (d) capacitor B? (e) What is the induced charge density s on the top surface of the dielectric? B A Figure 25-59 Problem 77.

You have many 2.0 mF capacitors, each capable of withstanding 200 V without undergoing electrical breakdown (in which they conduct charge instead of storing it). How would you assemble a combination having an equivalent capacitance of (a) 0.40 mF and (b) 1.2 mF, each combination capable of withstanding 1000 V?

A parallel-plate capacitor has charge q and plate area A. (a) By finding the work needed to increase the plate separation from x to x  dx, determine the force between the plates. (Hint: See Eq. 8-22.) (b) Then show that the force per unit area (the electrostatic stress) acting on either plate is equal to the energy density 0E2 /2 between the plates.

A capacitor is charged until its stored energy is 4.00 J. A second capacitor is then connected to it in parallel. (a) If the charge distributes equally, what is the total energy stored in the electric fields? (b) Where did the missing energy go?