College Physics (4th Edition)

We can rank the experiments in order of the stopping potential, from largest to smallest: $d \gt a = b \gt e \gt c$
We can find $K_{max}$ in each case: (a) $K_{max} = E-\phi = 2.8~eV-2.0~eV = 0.8~eV$ (b) $K_{max} = E-\phi = 3.0~eV-2.2~eV = 0.8~eV$ (c) $K_{max} = E-\phi = 3.0~eV-2.8~eV = 0.2~eV$ (d) $K_{max} = E-\phi = 3.0~eV-2.0~eV = 1.0~eV$ (e) $K_{max} = E-\phi = 2.8~eV-2.4~eV = 0.4~eV$ Note that the stopping potential is proportional to the maximum kinetic energy. We can rank the experiments in order of the stopping potential, from largest to smallest: $d \gt a = b \gt e \gt c$