What does the surface of the tube in an Electron Gun do when struck by electrons?

When electrons in an electron gun strike the surface of the tube, they transfer energy to the atoms or molecules in that surface. This energy transfer can excite the atoms on the surface, causing them to emit photons, which are particles of light. This phenomenon produces visible light, resulting in the glowing effect observed.

This occurrence is often related to the principles of photoluminescence or cathodoluminescence, where the incoming electrons contribute energy that leads to the emission of light as the excited atoms return to their ground state. The specific characteristics of the glow, including its color and intensity, depend on the material of the tube's surface and the energy of the electrons.

In summary, the correct answer highlights the relationship between the excitation of surface atoms by impacting electrons and the resulting emission of light, aligning well with the principles of how particle interactions lead to observable effects in materials.