Given, first incident energy, Ei1=2 (work function φ0 ) Second incident energy, Ei2=10φ0 If v1 and v2 be the respective maximum velocities in two cases, then by using the concept of photoelectric effect, KE=Ei−φ0 KE=Ei−φ0 ∴‌‌1∕2mv12=2φ0−φ0=φ0 . . . (i) and ‌‌1∕2mv22=10φ0−φ0=9φ0 . . . (ii) On dividing Eq. (i) by Eq. (ii), we get (‌