Acharge of -6.50 nC is spread uniformly over the surfaceof a nonconducting disk of radiu 1.25 cm. (a) Find the magnitude and direction of the electric fieldthis disk produces at a point P on the axis of the disk a distanceof 2.00 cm from its center. (b) Suppose that the charge were all pushed away from thecenter and distributed uniformly on the outer rim of the disk. Findthe magnitude and direction of the electric field at point P. (c) If the charge is all brought to the center of the disk,find the magnitude and direction of the electric field at pointP. (d) Why is the field in part (a) stronger than the field inpart (b)? Why is the field in part (c) the strongest of the threefields? Acharge of -6.50 nC is spread uniformly over the surfaceof a nonconducting disk of radiu 1.25 cm. (a) Find the magnitude and direction of the electric fieldthis disk produces at a point P on the axis of the disk a distanceof 2.00 cm from its center. (b) Suppose that the charge were all pushed away from thecenter and distributed uniformly on the outer rim of the disk. Findthe magnitude and direction of the electric field at point P. (c) If the charge is all brought to the center of the disk,find the magnitude and direction of the electric field at pointP. (d) Why is the field in part (a) stronger than the field inpart (b)? Why is the field in part (c) the strongest of the threefields?
Explanation / Answer
For a uniformly charged ring E = Q x / (4 0 (x2 +a2)3/2) where Q is total charge onring E = -9 * 10E9 * 6.5 * 10E-9 *0 .02 / (0.01252 +0.0202)3/2 = plug in values and do caliculations = ----- -N/C a = radius and x = distance from center If all of the charge is at the center then E = Q / (4 0 / x2) and the field is directed axiallytowards the center of the disk since electric field lines end onnegative charges = plug in values and do caliculations = ----- -N/C a = radius and x = distance from center If all of the charge is at the center then E = Q / (4 0 / x2) and the field is directed axiallytowards the center of the disk since electric field lines end onnegative charges