In a photo electric experiment 4 electrons with varying kinetic energy come out.
E1=1.6×10−19JE2=2.1×10−19JE3=3.2×10−19JE4=1.2×10−19J
The stopping potential , given this data will be
Stopping potential is the potential required to stop the highest energy electrons from just hitting the collector.
The highest energy electron in the given setup is E3=3.2×10−19J
and energy is conserved , that we know for sure.
Initially the electron has kinetic energy = 3.2×10−19J
Finally it stops, so final K. E = 0
K.E. lost = 3.2×10−19J …(i)
P.E. gained = qΔV
= −1.6×10−19(0–V0)
= (1.6×10−19)V0 …(ii)
3.2×10−19=1.6×10−19V0
V0=2 volt.