Practice Problems 1. What is the electric flux through a rectangular plate tilted at 25 degrees from the horizontal with a length of 43cm and a width of 21cm if the electric field (parallel to the ground) is 4.00kN/C? 2. Consider an infinitely long, positively charged wire with charge per unit length of . What is the magnitude of the electric field at a distance r from the wire? 3. What is the magnitude of the electric field inside a conducting sphere of radius r? Derive an expression for the magnitude of the electric field at a distance a from the center of the sphere (a>r). 4. Problem solving - Flux and Gauss' law Consider an infinitely long, very thin metal tube with radius R=2.90 cm. The above figure shows a section of it. If the linear charge density of the cylinder is 2=1.50E-8 C/m, what is the approximate magnitude of the electric field at radial distance I=2R? The value of the permittivity constant is 80=8.85E-12 C2/N.m2