Discovered by P. Villard (1860-1934) in 1900. 

Gamma rays are emitted from the nuclei of some radioactive elements such as uranium, radium etc.  

Properties 

1)  They are highest energy EM waves. (energy range keV-GeV)  

2)  They are highly penetrating.  

3)  They have a small ionising power. 

4)  They kill living cells. 

Uses

1)  Used as insecticide disinfection for wheat and flour. 

2)  Used for food preservation.  

3)  Used in radiotherapy for the treatment of cancer and tumour.  

4)  They are used to produce nuclear reactions.