Question

Why is a lead plate used in Rutherford's alpha-particle scattering experiment?

Answer 1

The Radioactive substance used in the experiment is kept in the Lead box.Lead has a very high density and Alpha,beta particles cannot penetrate through it(lead).This helps to concentrate the beam of this particles towards the gold foil.Also this particles if penetrate through body,it may destroy the DNA and contribute to the effect of carcinogenicity.So,for this reason Lead plate box of sufficient thickness is used in this experiment.