de-Broglie proposed dual natrue for elecrton by putting his famous equation ` lambda = ( lambda) /( mu)`, Later on Heisenberg proposed uncertiainty principle as . `Deltap.Deltaxle(h)/(2)(h=(h)/(2pi))` . On the contray particel natrue of electron wa estabilshed on the basis fo photoelectric effect . When a photon strikes the metal suface it given up its energy to the electro . Part of this enrgy ( say W) is used by the electrons to escpe form the metal and the remaining imparts he kinetc enrgy `(1//2 mu^2)` to photoeleton . The potential applied on the surface to reduce the velocity fo photoelecton to zero is known as stoppong potential
The element mlst commonly used in photoelectric cell is :
A. `Na`
B. `Ba`
C. `Cs`
D. `Ni`
