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Department of Physics PHYS 245 : Electromagnetism I Problem Set 4 Please hand in your solutions in class on Monday, 8. October, 2018. I. The charge density in a cylindrical region bounded by = =0 and = - [ is given by pm -best. where b and & are constants and = is in the axial direction. (a) Determine the electric field E(=) along the axis of the cylinder at a point p which is at 1 > > >0. (b) Show that the field is conservative. (c) Determine the potential difference between points = = 0 and = = 1. (d) Find the work done in moving a charge +2q from = = 0 to = = 1. 2. (a) Calculate the electric potential a point p distant z above the center of a disk with a circular hole in it (Figure 1), if it carries a uniform charge density o. The radius of the hole is a, while the radius of the disk is b. (b) Calculate the electric field at the point p. (c) If a charge q were placed at the centre of the disk, what would be the instantaneous force acting on it? Figure 1