Question

What should be the potential difference applied between the plates to accelerate the proton such that they have wavelength 300nm?

Answer 1

I hope you know the de-Broglie equation:

λ= h/mv

We also know that the stopping potential of an electron due to photo electric effect is equal to the maximum kinetic energy of electrons:







Substituting the values of e(charge on an electron, m(mass of alpha particle), h(Plank’s constant)