Properties of Cathode Rays

In summary, the ability of cathode rays to penetrate thin metal films is due to the mostly empty space within the atoms of the metal. However, the concept of empty space is not as simple at the quantum level, as it is filled with potentials and fields. The exact definition of "empty space" is debated and can affect how we interpret the passage of electrons through thin metal sheets.
  • #1
krisn
4
0
Why are cathode rays able to penetrate very thin metal films?
 
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  • #2
because thin metal films are mostly empty space
 
  • #3
Is this the empty space within the atom (ie the space between the nucleus and the electrons) or the space between the atoms in the metal lattice?

Thanks
 
  • #4
It seems as if you have a picture in your mind of the lattice as being the same as the common figure given as atoms being points connected by lines, with a whole lot of empty space. . Or is it the other common picture as atoms being hard balls to show the packing structure with empty space between the spheres.
Both are just geometrical representations.

A whole bunch of nucleii in specific locations surrounded by electron clouds in the 'space' between is short and sweet, and hopefully answers your question and does not cause the ire of most physicists as lacking detail, which is evident.
 
  • #5
Thanks for the reply

I was thinking of the structure where the atoms are represented as hard balls, in order to show the packing structure of the unit cell of the lattice. Based on the type of unit cell (eg face centred cubic or body centred cubic), it is possible to calculate the percentage of empty space in the unit cell of a lattice. However, such a representation is an oversimplficiation as it does not take into account the difficulty in defining the volume occupied by the electron cloud.

If electron clouds are considered, is there actually any spaces between the atoms (or more correctly ions) in the metallic lattice? If there is no space between atoms, then the cathode rays are really passing through the empty space within the atom, rather than spaces between the atoms. This is what I am trying to clarify.

Thanks
 
  • #6
krisn said:
If electron clouds are considered, is there actually any spaces between the atoms (or more correctly ions) in the metallic lattice? If there is no space between atoms, then the cathode rays are really passing through the empty space within the atom, rather than spaces between the atoms. This is what I am trying to clarify.

Thanks

That depends on what you mean by "empty space". The space inside an atom is full of possible positions for electrons and nuclei in addition to the different forces between each particle. You could also consider the space between each atom the same way.
 
  • #7
So Drakkith, are you saying that the space between atoms is actually the space between the nucleus and the electrons in an atom because the volume of space in which an electron could be is cannot be exactly be defined (we only know regions where electrons are most likely to be found).

Thanks
 
  • #8
krisn said:
So Drakkith, are you saying that the space between atoms is actually the space between the nucleus and the electrons in an atom because the volume of space in which an electron could be is cannot be exactly be defined (we only know regions where electrons are most likely to be found).

Thanks

I'm just saying that trying to determine whether an electron passes through "empty space" when it passes through a thin metal sheet depends entirely upon what you define as "empty space". At the quantum level things are not always defined the same way as they are at our own scale. Empty space within and between atoms is full of potentials and fields and whatnot. I wish I knew quantum physics a little better, perhaps I could explain it more accurately.
 

1. What are cathode rays?

Cathode rays are streams of electrons that are emitted from the negative electrode, or cathode, in a vacuum tube. They were first discovered by British physicist J.J. Thomson in the late 19th century.

2. What are the properties of cathode rays?

Cathode rays have several properties, including the ability to be deflected by electric and magnetic fields, the ability to cause fluorescence in certain materials, and the ability to produce heat when they strike a surface.

3. How are cathode rays produced?

Cathode rays are produced when high voltage is applied to a cathode in a vacuum tube. This causes electrons to be released from the cathode and accelerated towards the anode, creating a stream of electrons.

4. How are cathode rays used?

Cathode rays have been historically used in cathode ray tubes (CRTs) for television and computer screens. They are also used in spectroscopy, electron microscopy, and particle accelerators.

5. What is the significance of cathode rays in the history of science?

The discovery and study of cathode rays led to a better understanding of the nature of electricity and the existence of subatomic particles. This laid the foundation for future advancements in physics, including the development of quantum mechanics.

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