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(c) A charged, non-conducting sphere, radius R, has a charge density p(r) = A/rª, and a total charge Q=+5 C. Calculate the electric field as a function of radius, Ei(r), and sketch a plot of E(r) against r, over the range from 0 <r<5R. State the value and units of A. (8 marks) (d) Explain briefly what the electric field inside a conductor is, and why it has this value. (2 marks) The sphere from question 1(c) is placed close to a sphere with the same form of charge distribution (p(r) = B/r¹), but with a total charge of -5 C. The centres of the spheres are separated by a distance Z, where Z-3R. Draw a diagram illustrating this configuration. To your diagram add the electric field lines, and the lines of constant electric potential for this system of charges. Finally, write an algebraic expression for the electric field along the line that runs between the centres of the spheres. (8 marks)