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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctHardMulti-step

JEE Main 4 August 2021, Shift 1, Physics Q5

Question 5 of 90 in this shift, Physics question 5 of 30, Section A.

Consider a Hydrogen atom in its first excited state, what is the expression of magnetic field at the centre due to the circular motion of electron in its orbit?
  1. (1)μ0e5πme2256ε03h5\frac{\mu_0 e^5 \pi m_e^2}{256 \varepsilon_0^3 h^5}
  2. (2)μ0e7πme28ε02h5\frac{\mu_0 e^7 \pi m_e^2}{8 \varepsilon_0^2 h^5}
  3. (3)μ0e7πme2256ε03h5\frac{\mu_0 e^7 \pi m_e^2}{256 \varepsilon_0^3 h^5}Official answer
  4. (4)Zero

Official answer

Option 3

NTA final key.

Chapter
Atoms

Same idea in other shifts

Asked 2× in all
  1. 2 Apr 2026, Shift 2 · Q47Using 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…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.