Ratio of Charge to Mass (e/m) for the Electron

Presume an apparatus (vacuum tube) is turned on to a constant voltage of 200V. A beam will now be observed on the glass envelope opposite the anode. Adjusting the current, I through the coil would show how the beams curves up into the sphere of the tube and eventually bends over to complete a full circle.

1) Using a compass, decide the direction of the magnetic field applied by the coil. Then, from the direction the electrons bend, decide whether their charge is positive or negative. EXPLAIN your rezoning.

2) Turning off the current to the coil. Use a permanent magnet with known north and south poles to apply a known magnetic field to the electron beam. From the direction of deflection of the electrons, decide whether their sign is positive or negative. Describe your reasoning.                     

3) Can you explain why the presence of the extra field distorts the electron's path?

4) How will Earth's field affect the motion of the electrons?