Question

The Rydberg constant for hydrogen atom is Ry. The Rydberg constant for positronium (a bound system composed of a positron and an electron) is-

• A. Ry
• B. 2Ry
• C. $\frac{Ry}{2}$
• D. $\frac{Ry}{4}$

Answer 1

Answer: (C)

$\frac{Ry}{2}$

Answer 2

Rydberg constant Ry µ m

for positronium atom reduced atom reduced mass is

m = $\frac{mM}{m + M}$

m = M = mass of positron = mass of electron.

m = $\frac{m}{2}$

$\frac{Ry'}{Ry}$ =$\frac{\mu}{m}$ = $\frac{1}{2}$

Ry¢ = $\frac{Ry}{2}$