I have C.elegans strain with YFP tagged to my protein of interest. So to visualize the YFP in fluorescent microscope which excitation light should I use?
A green (like for GFP) filter will usually work, but you may need a different filter set if you're combining with other colors such as CFP. Check out fpbase.org (no affiliation) for tons of info on fluorescent proteins. Also, the fluorescent protein spectra are often on Addgene, if you got your plasmid from there.