Happens when a nuclei is unstable so released alpha particles to get to a more stable state.

Happens when an nucleus undergoes nuclear rearrangement.

Emission of energy in particles or EM waves from unstable nuclei in a random process to become stable, the nucleus decays

A positron (electron antiparticle) is released from a proton changing into neutron and positron.

An electron is released from a neutron changing into proton and eletron.

Different parts of it are covered by different thickness and type of materials to see the type of radiation.

Ionising radiation passes through the mica window and ionises the atoms, the cations and electrons move to the oppositely charged parts causing a current to flow through and cause a click.

When eletrons were discovered, people thought they were embedded into a positive 'dough' as 'currants' leading to the plum pudding model.

Due to the Rutherford alpha particle experiment where alpha particles were shot through a gold foil to see how they will pass through. Most were transmitted so the atom was mostly empty space, some were deflected so there was a positive nucleus and some were reflected so the nucleus was very small.