The cathode ray tube (CRT-ME Tube) is a classic vacuum demonstration device designed specifically for high school and university physics teaching and science popularization demonstrations. The electron beam inside the tube undergoes linear motion under the action of a high-voltage electric field and can undergo significant deflection under the action of an external magnetic field, visually demonstrating the influence of Lorentz force, left-hand rule, and magnetic field on the moving charge. Experimental case: Verify the left-hand rule: change the direction of the magnetic pole and observe the bending direction of the electron beam; By focusing the electron beam into a point through a longitudinal magnetic field, demonstrate the principle of electron lens.