Question

A sodium atom emits a photon of wavelength $590nm$ and recoils with velocity $v$ equal to

• A. $0.029m/s$
• B. $0.048m/s$
• C. $0.0023m/s$
• D. data inadequate

Answer 1

The correct option is A $0.029m/s$

Here momentum is conserved.

Momentum of photon rejected.

$\frac{h}{\lambda }=\frac{6.30\times {10}^{-34}}{590\times {10}^{-9}}$

Momentum of $Na$ atom

$=3.817\times {10}^{-35}Kg\times Velocity$

$\frac{h}{\lambda }=mv$

$V=\frac{h}{\lambda m}=\frac{6.30\times {10}^{-34}}{590\times {10}^{-9}\times 3.817\times {10}^{-35}}$

$=0.029m/s$