Question

A stationary hydrogen atom emits photon corresponding to the first line of Lyman series. If R is the Rydberg's constant and M is the mass of the atom, then the velocity acquired by the atom is (neglect energy absorbed by the photon)

• A. $\frac{3Rh}{4M}$
• B. $\frac{4M}{3Rh}$
• C. $\frac{Rh}{4M}$
• D. $\frac{4h}{Rh}$

Answer 1

Answer: (A)

$\frac{3Rh}{4M}$

Answer 2

p = - mv $\frac{h}{\lambda}$ = mv $\Rightarrow$ v = $\frac{h}{m} \left( \frac{1}{\lambda} \right)$ & $\frac{1}{\lambda} = \frac{3R}{4}$