Q.

When a hydrogen atom going from n=2 to n=1 emits a photon, its recoil speed is x/5 m/s. Where x= ______.

(Use: mass of hydrogen atom = 1.6×10-27kg)               [2024]


Ans.

(17)

The hydrogen atom transitions from n=2 to n=1,

ΔE=-10.2 eV

Recoil speed v=ΔEmc

                        =10.2 eV1.6×10-27×3×108=10.2×1.6×10-191.6×10-27×3×108

v=3.4 m/s=175 m/s

Therefore, x=17