How the magnetic field at the centre due to the orbiting electron depends on n

The same question, asked 2 times: 14 May 2024 S1, 21 Apr 2025 S2. Every wording below, oldest first.

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Question 1
14 May 2024 S1
13 $n$
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Question 2
21 Apr 2025 S2
24 $An electron moves in Bohr orbit. The magnetic field at the centre is proportional to$
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