I'm trying to learn Gauss's law and I'm having trouble with these two questions.1. Consider a long cylindrical charge distribution of radius R = 17 cm with a uniform charge density of ρ = 17 C/m3. Find the electric field at a distance r = 35 cm from the axis. I know E= 2k_e*(lamda/r), but the question gave rho, which is confusing me.2. A 12 g piece of Styrofoam carries a net charge of -9.1 ?C and floats above the center of a large horizontal sheet of plastic that has a uniform charge density on its surface. What is the charge per unit area on the plastic sheet? I got to the point where I had the charge density = -mg(epsilon_0)/q, but apparently that is not the correct answer, and I don't know where to go from here.Any help is appreciated. Thanks :)
1. Since it's a volume charge distribution , charge = rho*volume . Take a cylindrical gaussian surface of length 'h' at distance r from the axis . Now , E*2pie*r*h = q/epsilon = rho*pie*r^2*h/epsilon . which gives E = rho*r/2epsilon . 2. The electric field due to non-conducting sheet is sigma/2epsilon which gives your answer sigma = -2mg(epsilon)/q . The electric field due to conducting plate is sigma/epsilon since it has two effective surfaces with charge . You must have got confused there . Hope this helps .
If the sector at distance R is E0, then it is likewise E0 at 2R. the sector of a limiteless airplane of fee has an identical importance everywhere (?/2?). This properly regular consequence of Gauss's regulation is defined in all difficulty-loose text textile books.
