A charged paint is spread in a very thin uniform layer over the surface of a pla

Question

A charged paint is spread in a very thin uniform layer over the surface of a plastic sphere of diameter 15.0 cm , giving it a charge of -39.0 C . Part B Find the electric field just outside the paint layer. Express your answer with the appropriate units. Enter positive value if the field is directed radially inward and negative value if the field is directed radially outward. Part C Find the electric field 5.00 cm outside the surface of the paint layer. Express your answer with the appropriate units. Enter positive value if the field is directed radially inward and negative value if the field is directed radially outward. A hollow, conducting sphere with an outer radius of 0.240 m and an inner radius of 0.200 m has a uniform surface charge density of +6.17 × 106 C/m2. A charge of -0.900 C is now introduced into the cavity inside the sphere. Part C What is the electric flux through a spherical surface just inside the inner surface of the sphere? Express your answer with the appropriate units.

Explanation / Answer

1)

If the charge is uniformly distributed on the surface of a sphere, the electric field outside the sphere will be the same

as if the entire charge were concentrated in the center of the sphere. The electric field inside the sphere would be

zero.

Because the electric field in a would be measured inside the (uniformly-charged) sphere, the electric field for part a

would be zero. For the other two cases, we get

E = q / (4or^2) = kq/r^2

b)

r = 0.15 m = 0.075, so the electric field would be

E = (9 x 10^9 x -39 x 10^-6) / 0.075^2

E = -6.24 x 10^7 N/C, the negative sign means the electric field is in toward the sphere.

c)

E = kq / r^2

E = (9 x 10^9 x -39 x 10^-6) / (0.075 + 0.05)^2

E = -2.2464 x 10^-7 N/C

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.