In an experiment on $\alpha$-particle scattering, $\alpha$-particles are directed towards a gold foil and detectors are placed in position $P, Q$ and $R$. What is the distribution of $\alpha$-particles as recorded at $P, Q$ and $R$?

The conclusion of $\alpha -$particle scattering experiment are as below:

(i) Very few particles suffers large angle deflection which is denoted by P.

(ii) Some particles suffers small angle deflection which is denoted by Q.

(iii) Most of the particles straightly passed through gold foil which is denoted by R.