Experimental evidence for the existence of electrons as a universal constituent of matter:

- J.J. Thomson's Cathode Ray Tube Experiment: In the late 19th century, J.J. Thomson conducted a series of experiments using cathode ray tubes. He observed that when a high voltage was applied across the tube, a stream of negatively charged particles was emitted from the cathode and traveled towards the anode. These particles were later identified as electrons. This experiment provided the first direct evidence for the existence of electrons as a universal constituent of matter.

- Millikan's Oil Drop Experiment: In 1909, Robert Millikan performed the oil drop experiment to determine the charge and mass of an electron. By balancing the gravitational force with the electric force on tiny oil droplets, he was able to calculate the charge of a single electron. This experiment confirmed the existence of electrons and provided a quantitative measurement of their charge.

Experimental evidence for electrons as material particles:

- Scattering experiments: Scientists have performed various scattering experiments using electrons to demonstrate their particle-like nature. For example, the Davisson-Germer experiment in 1927 showed that electrons can be diffracted by a crystal lattice, similar to X-rays. This diffraction pattern confirmed that electrons behave as material particles with wave-like properties.

- Electron microscopy: Electron microscopes use a beam of accelerated electrons to create highly detailed images of objects at the atomic scale. The fact that electrons can be focused and manipulated to form images demonstrates their particle-like behavior and material nature.

- Electron interference: Similar to light waves, electrons can also exhibit interference patterns when passing through a double-slit experiment. This phenomenon, observed in the electron interference experiment, further supports the idea that electrons possess both particle and wave-like properties.

Evidence for the considerable energy of cathode rays:

- Heating effect: When cathode rays strike a solid object, they can produce heat due to their energy. This heating effect can be observed by the rise in temperature of the object. The magnitude of the temperature increase depends on the energy carried by the cathode rays, indicating that they possess considerable energy.

- Luminescence: Cathode rays can cause certain materials to emit light when they strike them. This phenomenon, known as luminescence, is a result of the energy transfer from the cathode rays to the atoms of the material. The intensity of the emitted light is directly related to the energy of the cathode rays.

- X-ray production: When cathode rays strike a metal target, they can generate X-rays. X-rays are high-energy electromagnetic radiation, and their production from the interaction of cathode rays with matter demonstrates the considerable energy carried by the cathode rays.

In conclusion, the experimental evidence from various studies, such as cathode ray tube experiments, scattering experiments, electron microscopy, and electron interference, supports the existence of electrons as a universal constituent of matter. Furthermore, observations of the heating effect, luminescence, and X-ray production provide evidence for the considerable energy carried by cathode rays.