If there is an electron moving towards an long straight wire at an angle theta. I am given the initial velocity of the electron and the distance it has to travel before being repelled away in the same plane. How would I go about finding the current in the wire required to repel the electron? I know that the magnetic field for a long wire is given by uI/2pir . I am wondering how to relate the speed of the electron to the strength of the magnetic field.