3. (a) What magnitude of magnetic field would make a beam of electrons, traveling to the right of this page at a speed of 4.8x106 m/s, go undeflected through a region where there is a uniform electric field of 8400 V/m pointing vertically upward? The magnetic field is known to be perpendicular to the electric field {Note: The electron mass is 9.11x10-31 kg, the electron charge is -1.60x10-1 C.} (b) What is the direction of the magnetic field if it is known to be perpendicular to the electric field? (c) What is the radius of the circular orbit of the electrons if the electric field is turned off? 1