Question

Which of the following is the correct expression for a reduced mass $\left(\mu \right)$ of a hydrogen like atoms ?
$($mass of electron $:m_e,$mass of nucleus $:m_n)$

• A. $\mu =\frac{m_e{m}_n}{m_e+m_n}$
• B. $\mu =\frac{m_e{m}_n}{m_e-m_n}$
• C. $\mu =\frac{m_e+m_n}{2m_n}$
• D. $\mu =\frac{2m_n}{m_e+m_n}$

Answer 1

The correct option is A $\mu =\frac{m_e{m}_n}{m_e+m_n}$

For the electron nucleus system of hydrogen like atoms, COM lies at the centre of the nucleus because electron mass is negligible as compared to the mass of proton and neutron and their reduced mass will be,

$\mu =\frac{m_e{m}_n}{m_e+m_n}$

Hence, option $\left(\text{A}\right)$ is correct.