Infra-red and ultra-violet rays

Often our students get confused about the status of the above two colours. In fact, both infra-red and ultra-violet are not colours because they are invisible to human eye. The word 'Infra' means 'below' or 'under' and infra-red is below the visible colour red while 'Ultra' means 'beyond' and ultra-violet is beyond the visible colour violet. The colours we can see are actually the visible parts of the electro-magnetic spectrum. The detail scientific importance about these colours can be learned from any advanced science or physics book.