Imagine looking at the face of a CRT. The bright spot where the electron beam hits that face is exactly in the screen's center. You bring a permanent magnet toward the body of the CRT vertically from above. The magnet is oriented vertically with its north pole downward. In what direction will the spot deflect?

Question

Quizplus · Accepted Answer

The electron beam in a CRT is deflected by magnetic fields due to the Lorentz force. When a magnet is brought near, the electrons experience a force perpendicular to both their velocity and the magnetic field. With the north pole of the magnet facing downward, the magnetic field is directed downward. Using the right-hand rule for negative charges (electrons), the force is directed to the left, causing the spot to deflect left.

Imagine Looking at the Face of a CRT