Question

An electron in the hydrogen atom jumps from excited state `n` to the ground state. The wavelength so emitted illuminates a photo-sensitive material having work function `2.75eV`. If the stopping potential of the photoelectron is `10V`, the value of `n` is
A. 3
B. 4
C. 5
D. 2

Answer 1

Correct Answer - B
`KE_(max) =10eV`
`phi =2.75 eV`
`E = phi+ KE_(max) = 12.75 eV` = Energy difference between `n =4 and n = 1 (n = 4)`
`rArr` value of `n = 4`