What is the role of the mercury vapour in a fluorescent tube?
A - AQA - A-Level Physics - Question 14 - 2021 - Paper 1
Question 14
What is the role of the mercury vapour in a fluorescent tube?
A. It absorbs photons of UV light and emits visible light.
B. It absorbs photons of visible light and... show full transcript
Worked Solution & Example Answer:What is the role of the mercury vapour in a fluorescent tube?
A - AQA - A-Level Physics - Question 14 - 2021 - Paper 1
Step 1
A. It absorbs photons of UV light and emits visible light.
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Answer
This option is correct. In a fluorescent tube, mercury vapour emits ultraviolet (UV) light when ionised. The UV light then interacts with the phosphor coating inside the tube, causing it to emit visible light.
Step 2
B. It absorbs photons of visible light and emits UV light.
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Answer
This option is incorrect. The mercury vapour does not primarily absorb visible light; instead, it generates UV light when excited.
Step 3
C. It emits photons of visible light following ionisation or excitation.
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Answer
This option is partially correct, but not complete. The mercury vapour emits UV light that is then converted into visible light by the phosphor coating, rather than emitting visible light directly.
Step 4
D. It emits photons of UV light following ionisation or excitation.
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Answer
This option is partially correct as it describes the behaviour of the mercury vapour. However, it does not accurately reflect the complete role in the context of the entire fluorescent tube operation.
