An electric charge q1 moving with the velocity v produces a magnetic field B given by B = r2 where r points from q1 to the point at which B is measured (Biot-Savart law, (b) Write out the corresponding magnetic force F21 that q2 exerts on q1. Define your unit radial vector. How do F12 and F21 compare?

An electric charge q1 moving with the velocity v produces a magnetic field B given by B = r2 where r points from q1 to the point at which B is measured (Biot-Savart law, (b) Write out the corresponding magnetic force F21 that q2 exerts on q1. Define your unit radial vector. How do F12 and F21 compare?