Question

If the Rydberg constant for hydrogen atom is $R$, then the Rydberg constant for positronium atom is

• A. $2R$
• B. $R$
• C. $R/2$
• D. $4R$

Answer 1

The correct option is C $R/2$

Given, electron in the positronium has reduced mass $\frac{m_e}{2}$.
As, energy is directly proportional to mass E becomes $\frac{E}{2}$.
Therefore, Rydberg's constant also becomes half.