Radiation corresponding to the transition n=4 to n=2 in hydrogen atoms falls on a certain metal (work function =2.5eV). The maximum kinetic energy of the photo-electrons will be: (A) .55ev (B) 2.55ev (C) 4.5ev (D) None

Radiation corresponding to the transition n=4 to n=2 in hydrogen atoms falls on a certain metal (work function =2.5eV). The maximum kinetic energy of the photo-electrons will be:
(A) .55ev
(B) 2.55ev
(C) 4.5ev
(D) None


Radiation corresponding to the transition
1/λ=RZ^2[1/n1^2−1/n2^2]

1/λ=RZ^2[1/2^2−1/4^2]

1/λ=RZ^2[3\16]

R=109678cm−1 and Z= Atomic no. of atom

1/λ=109678×12×316=20564cm^−1

λ=120564cm

KEmax=hc/λ−Φ

After putting the value of \lambda, h and c in CGS

KEmax= hc/λ−2.5ev=0.55ev