Question:medium

Angular momentum of an electron in an orbit of radius R of a hydrogen atom is directly proportional to

Updated On: Mar 19, 2026
  • R
  • 1/R
  • 1/√R
  • √R
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The Correct Option is D

Solution and Explanation

To determine how the angular momentum of an electron in an orbit of a hydrogen atom relates to the radius \(R\), we start with the quantized angular momentum condition for hydrogen:

The angular momentum \(L\) of an electron in orbit is given by: 

\(L = n \hbar\)

where \(n\) is the principal quantum number (an integer) and \(\hbar\) is the reduced Planck's constant.

For a hydrogen atom, the radius of the nth orbit is given by the Bohr radius formula:

\(R_n = n^2 \frac{\hbar^2}{m e^2}\)

where

  • \(m\) is the mass of the electron,
  • \(e\) is the charge of the electron, and
  • \(\hbar\) is the reduced Planck’s constant.

 

Solving the relationship between angular momentum and radius:

Since we have \(R \propto n^2\) and \(L = n \hbar\), given \(L \propto n\), if we solve for \(n\) in terms of \(R\), we have \(n \propto \sqrt{R}\).

Thus, the relation of angular momentum to radius \(R\) is:

\(L \propto \sqrt{R}\)

Therefore, the correct answer is \(\sqrt{R}\).

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