Question

An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function $2.75 \,eV$. If the stopping potential of the photoelectron is $10 \,V$ , then the value of $n$ is

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

Answer: (B)

3

Answer 2

$E _{ Ph } = K \cdot E _{\max }+ W$
$= eV _{0}+ W =10+2.75=12.75\, eV$

Differenced of $4$ and $1$ energy level is $12.75\, eV$
So higher energy level is $4$ to ground and Excited state is $n =3$