# Cathode Ray Tubes: Striations, Pressure & Momentum

• Spastik_Relativity
In summary, the striations in a cathode ray tube are caused by the ionization of particles by electrons, and the rotating wheel experiment proves that cathode rays carry energy and momentum.
Spastik_Relativity
After only recently learning about Cathode ray tubes at school i was taught that the striations caused in the tubes were the result of ionisation on the particles within the tube. Though this seems most correct i have also read in textbooks and been told by others a couple of other reasons for striations. Such as variations in pressure(in a textbook i read but i don't think its very likely) and electrons traveling through the tubes(basically ionising but the explination was a little different). If someone would happen to know the correct reason your help would be much appreciated.

Also, to do with cathode ray tubes in, particlular the rotating wheel in a tube prac, we were taught that this experiment proves the property that cathode rays carry energy AND momentum. I understand they carry energy but i am not so convinced THEY themselves carry momentum. If anyone could please clarrify.

Cheers!

The striations in a cathode ray tube are caused by the electrons that travel through the tube. They ionize the particles in the tube, creating charged areas which cause the striations. The variations in pressure could be caused by the electrons as well, but this is not the primary cause.The rotating wheel experiment does indeed prove that cathode rays carry energy and momentum. This is because the momentum of the electron can be measured by the force it applies to the wheel, causing it to rotate. This force is caused by the momentum of the electron, and thus proves that they carry momentum.

Thank you for sharing your thoughts and questions about Cathode Ray Tubes (CRTs). The striations in CRTs are indeed caused by ionization of particles within the tube. This is due to the electric field created by the charged particles within the tube, which causes the particles to accelerate and collide with gas molecules, leading to ionization. The variations in pressure within the tube can also contribute to the formation of striations, as gas molecules at different pressures will have different ionization rates.

As for the question about momentum, it is correct that cathode rays carry both energy and momentum. This was demonstrated by the rotating wheel experiment, where the movement of the wheel was caused by the momentum of the cathode rays. This is because cathode rays are made up of charged particles (electrons) that have both mass and velocity. When these particles collide with the wheel, they transfer their momentum to it, causing it to rotate. This phenomenon is also known as the "radiation pressure" of cathode rays.

I hope this helps clarify your understanding of CRTs and their properties. It's great that you are curious and seeking to understand more about this topic. Keep exploring and asking questions!

## 1. What are striations in a cathode ray tube?

Striations in a cathode ray tube refer to the distinct bands or lines of light that can be seen on the screen. These lines are caused by the interaction between the electrons emitted from the cathode and the gas molecules present in the tube.

## 2. How does pressure affect the striations in a cathode ray tube?

The pressure inside a cathode ray tube can significantly affect the appearance of striations. Higher pressures can lead to thicker and more distinct striations, while lower pressures can cause them to become faint or even disappear.

## 3. What is the relationship between pressure and momentum in a cathode ray tube?

The pressure inside a cathode ray tube is directly related to the momentum of the electrons. As the pressure increases, the electrons have more collisions with gas molecules, resulting in a change in direction and a decrease in momentum.

## 4. How does the pressure in a cathode ray tube affect the movement of electrons?

The pressure inside a cathode ray tube plays a crucial role in controlling the motion of electrons. Higher pressures can lead to more collisions, causing the electrons to follow a zigzag path and resulting in a diffused beam on the screen. Lower pressures allow for a more direct path and a focused beam.

## 5. Why are striations important in understanding cathode ray tubes?

Striations provide valuable insights into the behavior of electrons in a cathode ray tube. They help us understand how pressure and momentum affect the movement of electrons, which is essential for optimizing the performance of these devices. Additionally, striations can also be used to diagnose potential issues or malfunctions in the tube.

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