A straight horizontal wire carries a current of 6.50 mA. An electron is moving above the wire a direction parallel to it and in the similar direction as the conventional current in the wire, at a constant velocity of 5.41e5 m/s. Suppose that the force of gravity acts on the electron and that the electron is moving parallel to the Earth's magnetic field, therefore that the only magnetic force on it comes from the field generated by the current in the wire.
(a) Find the magnitude of the upward force that the magnetic field must exert on the electron to keep it at a constant velocity?
(b) Calculate how far is the electron above the wire?