Stopping potentials of are measured for photoelectrons emitted from a certain element when it is irradiated with monochromatic
-rays. The element is used as a target in an
-ray tube. The energy of
line is -
Let be the binding energies of
shell. Let
be energy of incident photon. Then
.........(1)
..........(2)
........(3)
Hence option 2 is correct.