Ionisation

EM radiation that has high-energy photons is more harmful than radiation with low-energy photons

Some EM radiation causes Ionisation

• Everything is made of atoms and molecules
• When a photon hits an atom or molecule, it sometimes has enough energy to remove an electron and change the atom or molecule
• This process is called ionisation
• It takes a lot of energy to remove an electron
• Only EM radiation with high enough photon energy can cause ionisation
• Ultraviolet, X-rays and gamma rays cause ionisation
• Some substances (radioactive materials) emit ionising gamma radiation 

Ionisation is dangerous if it happens in your cells

• Your cells can be damaged by ionising radiation
• …