A proton (charge +1.60 x 10-19 C) and an electron (charge -1.60 x 10-19 C) are both moving in the xy-plane with the
same speed, 5.20 x 105 m/s. The proton is moving in the +y-direction along the line x = 0, and the electron is moving in
the -y-direction along the line x = +4.00 mm. At the instant when the proton and electron are at their closest approach,
what is the magnitude of the magnetic force that the proton exerts on the electron?
