ferrous & non-ferrous

Cliciwch isod i weld yn Google Slides neu "edit" os oes gynych yr hawl:

https://docs.google.com/presentation/d/1I95PK3T-RA5xBfARb6mJER35bDCwN9fVpXhN3b4_stM/edit#slide=id.g2771b6dca0_0_46