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JEE Main 2026 (2 Apr, Shift 2) · Bohr Model: Orbits, Speed & Angular Momentum

Bohr Model: Orbits, Speed & Angular Momentum question from JEE Main 2026 (2 Apr, Shift 2)

Q26JEE Main 2026 · 2 APR · SHIFT 2Medium

Bohr Model: Orbits, Speed & Angular Momentum

Using Bohr’s model, calculate the ratio of the magnetic fields generated due to the motion of the electrons in the 2nd and 4th orbits of hydrogen atom ________.

Numerical answer type. Work it out, then open the answer.

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Answer: 32

  1. B=μ0I2rB = \frac{\mu_0 I}{2r} with I=ev2πrI = \frac{ev}{2\pi r}, so B∝vr2B \propto \frac{v}{r^2}
  2. v∝1nv \propto \frac{1}{n}, r∝n2⇒B∝1n5r \propto n^2 \Rightarrow B \propto \frac{1}{n^5}
  3. B2B4=(42)5=32\frac{B_2}{B_4} = \left(\frac{4}{2}\right)^5 = 32
  4. So the answer is 32.
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