question_answer

In a Frank-Hertz experiment, an electron of energy 5.6 eV passes through mercury vapour and emerges with an energy 0.7 eV. The minimum wavelength of photons emitted by mercury atoms is close to- [JEE Main 12-Jan-2019 Evening]

A) 220 nm

B) 1700 nm

C) 250 nm

D) 2020 nm

Correct Answer: C

Solution :

[c] The minimum wavelength of emitted photons is