Question

Understanding Physics - Problem 3)

Part 1) The figure is a section of a conducting rod of radius R₁ = 1.40 mm and length L = 14.40 m inside a thin-walled coaxial conducting cylindrical shell of radius R₂ = 11.1R₁ and the (same) length L. The net charge on the rod is Q₁ = +3.72 × 10^-12 C; that on the shell is Q₂ = -2.12Q₁. What are the (a) magnitude E and (b) direction (radially inward or outward) of the electric field at radial distance r = 2.28R₂? What are (c) E and (d) the direction at r = 5.24R₁? What is the charge on the (e) interior and (f) exterior surface of the shell?

Part 2) In the figure a small, nonconducting ball of mass m = 1.1 mg and charge q = 1.5 × 10^-8 C (distributed uniformly through its volume) hangs from an insulating thread that makes an angle θ = 35° with a vertical, uniformly charged nonconducting sheet (shown in cross section). Considering the gravitational force on the ball and assuming the sheet extends far vertically and into and out of the page, calculate the surface charge density σ of the sheet.

Answer 1