1. The problem statement, all variables and given/known data Referring to the magnetic field in a solenoid: "The field at exterior points is weak because the field due to current elements on the upper potions tends to cancel the field due to current elements on the lower portions" Why do the upper and lower potions cancel the magnetic field? 2. Relevant equations Bio-Savart Law 3. The attempt at a solution This is suppose to to explain why the magnetic field outside a solenoid is zero, but I am not sure why. When I draw the components of the current creating the magnetic field outside a solenoid, they do not cancel out. Is my reasoning incorrect?