3. In the network shown above, C1 = 6 UF, C2 = 3 UF, C3 = 4 HF, and C4 = 8 JF. A potential difference Vab is applied between points a and b. After the charges on the capacitors have reached their final values, the voltage across C3 is 40 V. C1 C2 a C3 b C4 What is the value of Vab?4. In Lecture 9 we saw that the energy density of an electric field is u = EOEZ /2. This \"electric-field energy\" is not a new kind of energy; it is simply a different way of interpreting electric potential energy. In particular, we can compute the total potential energy of a charge distribution from the energy density. Previously we had calculated the total potential energy for a collection of point charges (see slide 13 in Lecture 6), but now we can calculate it for continuous charge distributions. The total potential energy of a charge distribution is the volume integral of the energy density over all regions of space: 1 U = I E6052 (11/ an space (a) Positive charge Q is distributed uniformly over the surface of a thin spherical shell of radius R. i. Find the electric field in all regions of space. ii. Calculate the total potential energy of this charge distribution using the integral above. (b) Positive charge Q is distributed uniformly throughout the volume of a solid sphere of radius R. i. Find the electric field in all regions of space. ii. Calculate the total potential energy of this charge distribution using the integral above. (Note: \"all regions of space\" really does mean all regions. In both cases, you need to integrate over the volumes inside and outside the sphere.)