Hi, I have a bit of a problem understanding one of the solutions for my assignment. 1. The problem statement, all variables and given/known data Normally we use the equation F = iL X B to find the force of a magnetic field on a wire with a current. One of the questions asks to find the force on a section of wire between x=3 and x= 1, the wire's current is in the the negative x direction. The magnetic field is something like B=3i+8.0x^2 They used integration to solve the problem, integrating the change of force from 1 to 3. I'm wondering why this is used? Is it because the magnetic field is not uniform (it's in terms of x)? If the magnetic field is uniform, could we just have done F = iL x B with 2 being the L? Thanks in advance!