[" The work function of nickle is "5eV" .When light "],[" of wavelength "2000A^(0)" falls on it,emits "],[" photoelectrons in the circuit.Then the potential "],[" difference necessary to stop the fastest "],[" electrons emitted is (given "h=6.67times10^(-34)Js" ) "],[[" 1) "10V," 2) "1.75V," 3) "1.2V" 4) "0.75V]]