1. The problem statement, all variables and given/known data Find the magnetic field from a proton at location r, with velocity v, if the cross-product of vxr is <0,0,6.2e4> and the magnitude of r is 7.34e-2 2. Relevant equations B⃗ =μ/4π * qv x r /r^2 3. The attempt at a solution Substituting in 10^7 for μ/4π 1.6e-19 for q <0,0,6.2e4> for v x r and (7.34e-2)^2 for r^2 I get 1.8413e-5. This is not the right answer, so I must be doing something wrong. I thought you simply had to substitute in the variables and calculate. Could someone give me a hint?