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Explain how electrons are (i) produced and (ii) accelerated in an X-ray tube. - Leaving Cert Physics - Question 10 - 2018
Question 10
Explain how electrons are (i) produced and (ii) accelerated in an X-ray tube.
Worked Solution & Example Answer:Explain how electrons are (i) produced and (ii) accelerated in an X-ray tube. - Leaving Cert Physics - Question 10 - 2018
Step 1
(i) produced
Answer
Electrons are produced in an X-ray tube primarily through a process known as thermionic emission. This occurs when the cathode, typically made of a tungsten filament, is heated to a high temperature. The heat energizes the electrons within the cathode material, providing them enough energy to overcome the work function of the material, allowing them to escape into the vacuum of the tube. This release of electrons results in a cloud of negative charge around the cathode.
Step 2
(ii) accelerated
Answer
Once the electrons are emitted from the cathode, they need to be accelerated towards the anode to generate X-rays. This acceleration is achieved by applying a high voltage between the cathode and the anode. Typically, voltages range from 20 kV to 150 kV in X-ray tubes. The high electric field created by this voltage causes the electrons to gain kinetic energy and rapidly accelerate towards the anode, where they interact with the target material (often tungsten) to produce X-rays.