1. The problem statement, all variables and given/known data The magnitude J of the current density in a certain wire with a circular cross section of radius R = 2.20 mm is given by J = (3.07 × 108)r2, with J in amperes per square meter and radial distance r in meters. What is the current through the outer section bounded by r = 0.917R and r = R? Givens R = 2.20 mm = 2.20E-3 J = (3.07E8)r^2 r = .917R (inner bound) r = R (outer bound) 2. Relevant equations Cross section of wire (area) = pi(r)^2 Current Density = J = I/A 3. The attempt at a solution Since we are attempting to find the current in a bounded section we need to subtract the outer bound area from the lower bound area: pi(R)^2 - pi(.917R)^2 = bounded section area Since we have the current density we can use I = JA: (3.07E8)r^2* ( pi(R)^2 - pi(.917R)^2) = 736.8 It wants the answer in mA so = 736000 mA It says my answer is incorrect, and I'm not sure where I went wrong.