Why Don't Electrons Stick to the Anode in a Cathode Ray Tube?

This means that the anode's voltage has no effect on the actual trajectory of the electrons. In summary, the cathode ray tube works by heating a filament which causes the cathode to emit electrons through thermionic emission. The anode, which is positively charged, attracts the electrons towards the screen but does not affect their trajectory as it is not in their path.
  • #1
alan4cult
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Homework Statement


I'm have a little problem with understanding the workings of a cathode ray tube. I understand that a filament is heated and that in turn heats the cathode which, due to thermionic emission emits electrons.

OK so here is my problem. A positively charged anode is used to attract the electrons towards the screen but how come the electrons do not stick to this "positively" charged anode but instead continue past it to the screen?

I hope you understand what I mean!

I'm sorry if I posted this in the wrong forum. I'm new here.
 
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  • #3


Dear student,

Thank you for reaching out with your question about the workings of a cathode ray tube. I am happy to help clarify this concept for you.

Firstly, you are correct in understanding that the cathode is heated to emit electrons through thermionic emission. These electrons are then accelerated towards the positively charged anode by an electric field. However, the reason why the electrons do not stick to the anode is due to the electric field created by the anode.

As the electrons approach the anode, they experience a repulsive force from the positively charged anode. This repulsive force is stronger than the attractive force between the anode and electrons, causing the electrons to continue their path towards the screen. Additionally, the anode is typically coated with a material that prevents the electrons from sticking to it.

I hope this explanation helps to clarify your understanding of the cathode ray tube. If you have any further questions, please do not hesitate to ask.

Best regards,

 

FAQ: Why Don't Electrons Stick to the Anode in a Cathode Ray Tube?

How does a cathode ray tube (CRT) work?

A CRT works by using a high voltage to accelerate electrons from the cathode (negative electrode) towards the anode (positive electrode) inside a vacuum tube. The electrons are focused and controlled by magnetic or electric fields to create an image on the screen.

What are the components of a cathode ray tube?

The main components of a CRT include the cathode, anode, electron gun, deflection coils, and phosphor-coated screen. The cathode emits electrons, the anode attracts and collects the electrons, the electron gun focuses and controls the electrons, the deflection coils guide the electrons to specific areas on the screen, and the phosphor-coated screen converts the electrons into visible light to create the image.

What is the purpose of the deflection coils in a cathode ray tube?

The deflection coils in a CRT are responsible for guiding the electrons to specific areas on the phosphor-coated screen. By varying the strength and direction of the magnetic fields produced by the deflection coils, the path of the electrons can be controlled to create different shapes and images on the screen.

How does the image on a cathode ray tube screen persist?

The phosphor coating on the screen of a CRT is designed to emit light when struck by electrons. As the electrons hit the phosphor, they cause it to glow, creating the image on the screen. This glow persists for a brief moment even after the electrons have moved on, allowing the image to remain visible until it is updated by new electrons.

What are the advantages and disadvantages of cathode ray tubes?

One advantage of CRTs is their ability to display high-quality images with good contrast and color accuracy. They also have fast response times, making them suitable for fast-moving images such as in video games. However, CRTs are bulky, consume a lot of power, and emit harmful radiation. They also have a limited viewing angle and are susceptible to screen burn-in. These factors have led to the development of newer, more efficient display technologies.

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