The maximum kinetic energy of the emitted electron is equal to work done on the electron to stop it to reach to the anode. Therefore

K.E_max = 1/2 mv²_max = eV₀

Magnitude of charge of the electron ‘e’ = 1.6 × 10^-19 C

V₀ = Stopping Potential

K.E_max = maximum kinetic energy of emitted electron

m = mass of the electron = 9.1 × 10^-31 kg

v_max = maximum velocity of electron

K.E_max = eV₀ = 1.6 × 10^-19 × 1.5 = 1.5 Ev

= 2.4 × 10^-19 J

maximum KE of electron is 2.4 × 10^-19 J