Question

In a Rutherford scattering experiment when a projectile of charge Z1 and mass M1 approaches a target nucleus of charge Z2 and mass M2, the distance of closest approach is r0. The energy of the projectile is :

Answer 1

Energy of the projectile is the potential energy at closest approach

Therefore energy ∝z1z2.

Answer 2

The energy of projectile will be equal to the potential energy at closest approach

U = k z1z2/r

Therefore energy is proptional to z1z2.