* Electron Beam: The picture tube works by using an electron beam that scans across the screen, exciting phosphors to create the image. Electrons are negatively charged particles, and their flow constitutes an electric current.

* Vacú: The tube is evacuated (a vacuum) to prevent the electron beam from colliding with air molecules and being scattered.

* Conductividad: La superficie interna del tubo de imagen está recubierta con un material conductor (generalmente una capa delgada de grafito) para ayudar a guiar el haz de electrones y evitar que acumule carga estática.

Therefore, the presence of the electron beam and the conductive coating on the inside of the tube makes the picture tube a conductor.