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Question

The angle of orientation (in degrees) of the angular momentum vector with respect to z-axis for $l = 2$ and $m_l = +2$ state of H-atom is ________ (up to two decimal places)

The angle of orientation ($\theta$) of the angular momentum vector ($\vec{L}$) relative to the z-axis depends on the magnetic quantum number ($m_l$) and the orbital quantum number ($l$).

Angle Calculation Formula

The cosine of the angle $\theta$ between the angular momentum vector and the z-axis is given by the quantum mechanical relationship:

$\cos(\theta) = \frac{m_l}{\sqrt{l(l+1)}}$

Applying Values for H-atom State ($l=2$, $m_l=+2$)

We are given the state parameters for the H-atom: $l=2$ and $m_l=+2$. First, calculate the denominator term $\sqrt{l(l+1)}$:

$\sqrt{l(l+1)} = \sqrt{2(2+1)} = \sqrt{2 \times 3} = \sqrt{6}$

Next, substitute the quantum numbers into the cosine formula:

$\cos(\theta) = \frac{+2}{\sqrt{6}}$

Evaluate the fraction:

$\cos(\theta) \approx 0.81649658$

Finally, compute the angle $\theta$ by taking the inverse cosine (arccos):

$\theta = \arccos\left(\frac{2}{\sqrt{6}}\right) \approx \arccos(0.81649658)$

$\theta \approx 35.264 \text{ degrees}$

Final Result

Rounding the result to two decimal places as required, the angle of orientation is $35.26^\circ$. This value is consistent with the provided range check (33.3 to 36.9 degrees).

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Important Questions from Angular Momentum

  1. The orbital angular momentum (L) of an electron is $\sqrt{12}\hbar$. The minimum angle between L and its z-component (in degrees) is ______ (rounded off to one decimal place).
  2. If a particle's state function is an eigenfunction of the operator $\hat{L}^2$ with eigenvalue $30\hbar^2$, then the possible eigenvalue(s) of the operator $\hat{L}_z^2$ for the same state function is/are
  3. The spherical harmonic function, $Y_{l,m}(\theta,\phi)$, with appropriate values of $l$ and $m$, is an eigen function of $\hat{L}_x^2 + \hat{L}_y^2$ operator. The corresponding eigenvalue is

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