Question

In a Geiger– Marsden experiment, calculate the distance of closest approach to the nucleus of Z =75, when an a-particle of 5MeV energy impinges on it before it comes momentarily to rest and reverses its direction.

How will the distance of closest approach be affected when the kinetic energy of the a-particle is doubled?

Answer 1

Let r0 be the distance of closest approach where the K.E of α-particle is converted into its potential energy.

Hence, the distance of closest approach is halved if K.E is doubled.