I need a typed answer as well as soon . Only typed answer by keyboard needed . Solve urgent please I will surely give a helpful rating for your answer if you solve fast and correctly.

_} Use Gauss's law to obtain an expression for E in free space due to an innitely long line of charge with uniform charge density pt along z-axis. Make a drawing. Under what circumstances is it useful? How should one choose a Gaussian surface? When is it reasonable to treat a charge distribution as a point charge