Please help me on this problem! A thin spherical shell made of plastic carries a
ID: 2138512 • Letter: P
Question
Please help me on this problem!
A thin spherical shell made of plastic carries a uniformly distributed negative charge -6e-10 coulombs (indicated as -Q1 in the diagram). Two large thin disks made of glass carry uniformly distributed positive and negative charges 1.7e-05 coulombs and -1.7e-05 coulombs (indicated as +Q2 and -Q2 in the figure). The radius R1 of the plastic spherical shell is 7 mm, and the radius R2 of the glass disks is 4 meters. The distance d from the center of the spherical shell to the positive disk is 18 mm.
(a) Find the potential difference V1 - V2. Point 1 is at the center of the plastic sphere, and point 2 is just outside the sphere.
volts
(b) Find the potential difference V2 - V3. Point 2 is just below the sphere, and point 3 is right beside the positive glass disk.
volts
Remember that the sign of the potential difference is important.
Explanation / Answer
A)
dV = -(QC/(pi*(R2^2))/e)*R1
dV = -((1.7e-5)/(3.1416*(4*4))/8.85e-12) * 0.007
dV = -268 V
B)
dV = -(((9*10^9)*((Qsphere/D)-(Qsphere/R1))) + (QC/(pi*(R2^2))/e)*(D-R1))
dV = -(((9e9)*((6e-10/0.018)-(6e-10/0.007))) + (1.7e-5/(3.1416*(4*4))/8.85e-12)*(0.018-0.007))
dV = -892 V