A cathode ray tube and an X-ray tube are practical applications of thermionic emission - Leaving Cert Physics - Question 10 - 2012
Question 10
A cathode ray tube and an X-ray tube are practical applications of thermionic emission. In these tubes thermionic emission releases electrons, which are then acceler... show full transcript
Worked Solution & Example Answer:A cathode ray tube and an X-ray tube are practical applications of thermionic emission - Leaving Cert Physics - Question 10 - 2012
Step 1
Name the parts labelled A, B, C in the diagram.
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Answer
A - cathode / hot metal
B - anode
C - screen
Step 2
Give the function of any two of these labelled parts.
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Cathode emits electrons when heated due to thermionic emission.
Anode attracts/accelerates electrons towards it.
Step 3
How can the beam of electrons be deflected?
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The beam can be deflected by an electric field, magnetic field, or by using X-Y plates.
Step 4
What happens at C when the electrons hit it?
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When the electrons hit the screen at C, they produce light, forming a visible spot or image.
Step 5
Why is a vacuum needed in a cathode ray tube?
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A vacuum is necessary to prevent the electrons from colliding with air molecules, which would scatter the beam and degrade the image quality.
Step 6
Draw a sketch of an X-ray tube.
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The sketch should represent the key components: an anode, cathode, glass tube, target, high voltage supply, and cooling fins.
Step 7
Give one safety precaution taken by a radiographer when using an X-ray machine.
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Radiographers use lead shielding to protect themselves from unnecessary exposure to X-rays.
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