According to Rutherford's experiment when a sample of radioactive substance is place in a lead box and permit the emission of radiation by a small hole only. When the radiation enters into the external electric field, they divide into three parts           

(i)         Radiations which deflects towards negative plate are known as alpha- rays (stream of positively charged particles)

(ii)        Radiations which deflects towards positive plate are known as Beta-particles (stream of negatively charged particles)

(iii)       Radiations which are undeflected known as Gamma rays. (E.M. waves or photons)