IBEW Apprenticeship 1st Year, 3rd Period (1-3) Practice Test 2025 - Free IBEW Apprenticeship Practice Questions and Study Guide

In a vacuum tube, the concept of photoemission refers to the process where electrons are emitted from a material (typically the cathode) when it is exposed to light (photons). When light strikes the cathode, it provides energy to the electrons, allowing them to overcome the work function of the material and escape into the vacuum.

Once these electrons are free in the vacuum, a positive plate, acting as the anode, creates an electric field that attracts these negatively charged electrons. This attraction leads to a flow of electrons from the cathode towards the anode. The presence of the positive plate is essential for this flow; without it, the emitted electrons would not have a directed path to move towards.

Thus, the statement that a positive plate in a vacuum tube causes electrons to flow towards it during photoemission is correct, as the positive charge of the plate indeed influences the direction of the electron flow, facilitating the movement from the cathode to the anode within the vacuum environment.