Rydberg Constant Dependence on Mass Number – Rankers Physics

Nucleus: Practice Problem & Solution

Assertion (A): Rydberg constant varies with mass number of a given element. Reason (R): The reduced mass of electron depends on the mass of the nucleus.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Nucleus. Understanding the underlying formula is key to arriving at the correct answer below:

The effective Rydberg constant for an atom depends on the reduced mass \( \mu = \frac{m_e M}{m_e + M} \), where \( M \) is the nuclear mass (related to mass number). So, (A) is true. The reduced mass clearly depends on the nuclear mass. So (R) is true. (R) correctly explains (A).

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