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 $2.75eV$. If the stopping potential of the photoelectron is $10V$, then the value of $n$ is :-

• A. $2$
• B. $3$
• C. $4$
• D. $5$

Answer 1

The correct option is B $3$

$E_{Ph}=K.E_{max}+W$
$=e{V}_0+W=10+2.75=12.75eV$
Differenced of 4 and 1 energy level is 12.75 eV
So higher energy level is 4 to ground and Excited state is $n=3.$