Outline the experimental study and the conclusion arrived in the `alpha` - scattering by a gold foil.

Explanation

The source of `alpha` - particles are taken from `alpha` - decay of `._(83)^(214)Bi` Gold foil used is of thickness 0.21 micron . The scattered `alpha` - particles were discovered by rotatable doctor with a fluorescent flashes on the screen . The intensity of `alpha` - particles is studied as the function of `'theta'`
According the law of conservation of energy
K.E = P.E.
i.e., `1/2 mv^(2)=1/(4piepsilon_(0))(2Ze^(2))/(r_(0))`
where `'r_(0)'` is the closest approach of `'alpha'` particle.
`:. r_(0) ((1)/(4piepsilon_(0)))(2Ze^(2))/(K)" where "K=1/2 mv^(2)`
Experimental conclusions :
The impact parameter `I_(p)=2r_(0) cot (theta//2)`
For a wide range of values of `theta , alpha` particles travel straight because of small deflection.
For `theta = 180^(@),I_(p) =0 " the " alpha` - particle when directed towards the centre (for a head - on collision), it retraces the path . Thus the impact parameter is inversely proportional to tan `(theta//2)`