26. Capacitors & Dielectrics

The 300 μF capacitor in FIGURE P30.75 is initially charged to 100 V, the 1200 μF capacitor is uncharged, and the switches are both open.<IMAGE>

a. What is the maximum voltage to which you can charge the 1200 μF capacitor by the proper closing and opening of the two switches?

Two 2.0 cm×2.0 cm metal electrodes are spaced 1.0 mm apart and connected by wires to the terminals of a 9.0 V battery.

a. What are the charge on each electrode and the potential difference between them?

Two 3.0-cm-diameter aluminum electrodes are spaced 0.50 mm apart. The electrodes are connected to a 100 V battery.

a. What is the capacitance?

Two 3.0-cm-diameter aluminum electrodes are spaced 0.50 mm apart. The electrodes are connected to a 100 V battery.

b. What is the magnitude of the charge on each electrode?

(II) A cylindrical capacitor (Example 24–2) has Rₐ = 3.5 mm and R₆.= 0.50 mm. The two conductors have a potential difference of 625 V, with the inner conductor at the higher potential.

(c) Calculate the electric field at the surface of the inner conductor.

(II) How strong is the electric field between the plates of a 0.80-μF air-gap capacitor if they are 2.0 mm apart and each has a charge of magnitude 84-μC?

The long cylindrical capacitor shown in Fig. 24–37 consists of four concentric cylinders, with respective radii Ra, R₆ , R꜀ and Rₔ. The cylinders b and c are joined by metal strips. Determine the capacitance per unit length of this arrangement. (Assume equal and opposite charges are placed on the innermost and outermost cylinders.)

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