Chapter 4: Q32E (page 810)
A capacitor is formed from two concentric spherical conducting shells separated by vacuum. The inner sphere has radius 12.5 cm, and the outer sphere has radius 14.8 cm. A potential difference of 120 V is applied to the capacitor. (a) What is the energy density at r = 12.6 cm, just outside the inner sphere? (b) What is the energy density at r = 14.7 cm, just inside the outer sphere? (c) For a parallel-plate capacitor the energy density is uniform in the region between the plates, except near the edges of the plates. Is this also true for a spherical capacitor?
Short Answer
(a)The energy density at just outside the inner sphere is:
(b) The energy density at just outside the inner sphere is
(c) No, the energy density is not uniformly distributed in the region between the plates except the near the edges of the plate.