A charged nonconducting rod, with a length of 2.00 m and a cross-sectional area of 4.00 cm2,

Question:

A charged nonconducting rod, with a length of 2.00 m and a cross-sectional area of 4.00 cm2, lies along the positive side of an x axis with one end at the origin. The volume charge density ρ is charge per unit volume in coulombs per cubic meter. How many excess electrons are on the rod if p is
(a) Uniform, with a value of – 4.00 µC/m3 and
(b) Nonuniform, with a value given by ρ = bx2, where b = – 2.00 µC/m5?