圖片參考:http://imgcld.yimg.com/8/n/HA01097219/o/701111230084713873404310.jpg
55. why the magnitude of E-field is (surface charge density)/(eo) but not (surface charge density)/2eo since a football field is a non-conductor?
56. Why Q' is the same as that of A (in part a, which I don't show it here)?
3. Why does a charge always move from high potential to low potential?
4. The magnitude of E-field between two thin, infinite conducting plate with surface charge density A is equal to A/e0, what about the an E-field between two thin, infinite conducting plate when one of them is charged and the other is not?
5. On an irregularly shaped conductor, why the surface charge density is greatest at locations where radius of curvature of the surface is smallest? Can some1 show the proof here or provide a website that contains the proof?
thanks
6. A charge distribution that is spherically symmetric but not uniform radially produces an E-field of magnitude E=Kr^4, directed radially outward from the center of the sphere. r is the radial distance from that center, and K is a constant. What is the volume density p of the charge distribution?
ans to 6: 6K(eo)r^3
7. A solid nonconducting sphere of radius R = 5.6 cm has a nonuniform charge distribution of volume charge density p=(14.1 pC/m3)r/R, where r is radial distance from the sphere's center. a:
(a) What is the sphere's total charge? What is the magnitude E of the electric field at (b) r=0, (c) r=R/2, (d) r=R? ans: a: 7.78fC, b: 0, c:5.58mN/C, d: 22.3mN/C
1. So what's the differences between σ/e and σ/2e? 2. For 7a, why it is 4pi r^2 but not 4/3 pi r^3 as p is volume charge density. please send the ans to my email if there is not enough space here