Question

An electron with kinetic energy = E eV collides with a hydrogen atom in the ground state. The collision will be elastic 

(a) for all values of E 

(b) for E < 10.2 eV 

(c) for E < 13.6 eV 

(d) only for E < 3.4 eV

Answer 1

Correct Answer is: (b) for E < 10.2 eV

Hydrogen atom in the ground state will only absorb energy greater than 10.2 eV. If this occurs, the collision will be inelastic. If there is no absorption of energy, the collision is elastic.