Gauss' Law

a)Using Gauss’ Law, derive an equation for the electric field E, at some distance r from an infinite line charge with a linear charge desity λ. State the magnitude and the direction. Use the Gaussian cylinder in the diagram.

b)Use the expression derived in part a) to determine the numerical value of the electric field for a lambda=1 X 10^-6C/m at a distance of 5 cm from the infinite line charge.

c)what is the magnitude and direction of the electric field if I replace the positive line charge with a negative line charge of the same magnitude charge density?