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The diagram shows the main parts of an X-ray tube - Edexcel - GCSE Physics - Question 6 - 2016 - Paper 1
Question 6
The diagram shows the main parts of an X-ray tube. electron beam high voltage supply vacuum heavy metal target (i) The electrons in the beam escape from a hot fila... show full transcript
Worked Solution & Example Answer:The diagram shows the main parts of an X-ray tube - Edexcel - GCSE Physics - Question 6 - 2016 - Paper 1
Step 1
The electrons in the beam escape from a hot filament. State the name of the process by which electrons escape from a hot filament.
Answer
The process by which electrons escape from a hot filament is called thermionic emission. This phenomenon occurs when the thermal energy of the filament causes electrons to gain sufficient energy to overcome the work function and escape into the vacuum.
Step 2
Explain why there must be a vacuum inside the X-ray tube.
Answer
A vacuum is necessary inside the X-ray tube for two main reasons:
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Prevent Collisions: The absence of air means that electrons can travel from the filament to the anode without colliding with gas molecules or particles. If there were air, these collisions could slow down the electrons or cause them to lose energy, thus reducing the efficiency of X-ray production.
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Maintain Electron Path: A vacuum ensures that the electrons maintain their high speed and trajectory towards the anode. Any presence of gas could lead to scattering or deflection of the electrons, which would hinder their ability to generate X-rays effectively.