Irish physicist G.J - Leaving Cert Physics - Question 10 - 2020

The mass of an electron is approximately $9.11 \times 10^{-31}$ kg, while the mass of a proton is about $1.67 \times 10^{-27}$ kg. Thus, the proton is roughly 1836 times more massive than the electron.

Thermionic emission refers to the process by which electrons are released from the surface of a heated metal. When the metal is heated to a high temperature, the thermal energy provides enough energy for the electrons to overcome the attractive forces holding them in the metal.

A labeled diagram of a cathode ray tube would typically include:

• Heated cathode (filament)
• Anode
• Electron beam path
• Deflection plates
• Glass envelope (vacuum)
• Screen for viewing output

This setup allows electrons to be emitted and directed based on the voltages applied to the anode and deflection plates.

Electrons in a cathode ray tube are commonly detected using a fluorescent screen, which emits light (or flashes) when struck by the high-energy electrons.

One use of a cathode ray tube is in older television sets and computer monitors, where it was used to create images on the screen by directing electron beams.

In an experiment to demonstrate the photoelectric effect, an apparatus such as a gold leaf electroscope is used. Steps include:

1. Charge the electroscope by placing a charged plate on the top.
2. Shine UV light on the zinc plate connected to the electroscope.
3. Observe that the electroscope discharges as the UV light causes electrons to be emitted from the zinc, collapsing the gold leaf due to loss of charge.

X-rays are a form of high-frequency electromagnetic radiation. They have wavelengths shorter than ultraviolet light and are capable of penetrating various materials, making them useful in medical imaging.

The production of X-rays occurs when high-energy electrons collide with a metal target, resulting in the emission of X-rays. This process involves conversion of kinetic energy into electromagnetic energy, whereas the photoelectric effect involves the absorption of light energy, causing electrons to be emitted from a material.

One danger associated with X-rays is that exposure can cause damage to living tissue and increase the risk of cancer, particularly with prolonged or repeated exposure.