Question

Could the electron beam in an oscilloscope tube (cathode-ray tube) be used as a compass? How? What advantages and disadvantages would it have in comparison with a conventional compass?

Answer 1

Sure it could.

Lorentz force (caused by Earth magnetic field) acts on moving electrons, the displacement in vertically is proportional to the angle between beam direction and south-north direction.

Disadvantages - this way is expensive, inconvenient, not-reliable.

Advantages – in principle may be automated and very precise.