Photons with energy  5eV are incident on a cathode C, on a photoelectric cell. The maximum energy of the emitted photoelectrons is  2eV.  When photons of energy  6eV are incident on  C, no photoelectrons will reach the anode  A if the  potential of A relative to  C is

Given Photon energy= 5eVThe maximum energy= 2eVFrom the Einstein’s photo electric equation, we getϕ=kmax−Eϕ ∴ϕ=5−2=3 eVNow, when photons of energy  6eV are incident, no photoelectrons are emitted. This is because a stopping potential is applied.∴eV0=Eϕ−ϕ=6−3=3eVV0=3VHence, a stopping potential of 3V has to be applied.Now, stopping potential is defined as the negative potential applied to the anode with respective to the cathode. Hence, stopping potential of  A with respective  C is  -3VSo, the correct option is (B)