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 the Value of n is.
As we learnt in
Lymen series -
When electron jump from higher orbital to 1st energy level
i.e. ground state
Energy of photon emitted from the hydrogen atom is
This is equal to energy gap between n=1 and n=4 in hydrogen atom.