# BEISER MODERN PHYSICS Rotational Energy Level

• MARX
In summary, the conversation is discussing the rotational spectrum of HCl and finding the distance between the hydrogen and chlorine nuclei in an HCl molecule. The person asking the question is wondering why they can't use the energy equation with only one of the given wavelengths to find the moment of inertia, and then use the reduced mass to calculate the distance. They mention that this method is not giving them the correct answer.
MARX

## Homework Statement

1. The rotational spectrum of HCl contains the following wavelengths:

12.03 10 5 m 9.60 10 5 m 8.04 10 5 m 6.89 10 5 m 6.04 10 5 m

If the isotopes involved are 1H and 35Cl, find the distance between the hydrogen and chlorine nuclei in an HCl molecule.

## Homework Equations

E = J(J+1)h^2/(2I)[/B]

## The Attempt at a Solution

I have the solution it says I have to use the difference in the frequency of above data
HERE IS MY QUESTION
why can't I apply the energy equation and use ONLY one of the wavelengths (E= hc/λ) to get the moment of inertia we know for longest λ above lowest energy hence J=0 There no
from there I know how to go from E to R using reduced mass
but that's not giving me the right answer [/B]

MARX said:
why can't I apply the energy equation and use ONLY one of the wavelengths (E= hc/λ) to get the moment of inertia we know for longest λ above lowest energy hence J=0 There no
from there I know how to go from E to R using reduced mass
but that's not giving me the right answer

## 1. What is rotational energy level in modern physics?

Rotational energy level refers to the quantized energy states of a rotating molecule or particle. In modern physics, this concept is used to explain the behavior of atoms, molecules, and other systems at the microscopic level.

## 2. How is rotational energy level calculated?

The rotational energy level of a molecule or particle can be calculated using the formula E = J(J+1)h^2/8π^2I, where E is the energy level, J is the quantum number for rotational momentum, h is the Planck's constant, and I is the moment of inertia of the system.

## 3. What is the significance of rotational energy level in modern physics?

The rotational energy level is an important concept in modern physics as it helps to explain the energy and stability of molecules, atoms, and other systems. It also plays a crucial role in understanding the spectra of these systems and their interactions with light.

## 4. How does rotational energy level differ from other energy levels?

Unlike the energy levels of electrons in an atom, which are related to their position and motion, rotational energy levels are related to the rotation of a molecule or particle. This means that rotational energy levels are not affected by external forces, but rather by the shape and composition of the system.

## 5. Can rotational energy levels be observed experimentally?

Yes, rotational energy levels can be observed experimentally through various techniques such as spectroscopy. By analyzing the frequencies of light absorbed or emitted by a system, scientists can determine the rotational energy levels and use this information to understand the behavior of the system.

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