Need help to meas noise v of a JFET
 

I need to measure the "equivalent noise voltage", in units of
nV/square root( hz) of a JFETs drain-source at a given Vds & Ids and
F=10 hz. How do I do that? What's throwing me is the F=10 Hz. What do
I do with that? I thought to take the measurement, I would bias the
FET to the required Vds and Ids and measure the voltage across the
drain - source with an RMS meter. Then divide that by the sqrt of the
bandwidth of the RMS meter. I've Googled, but didn't find anything to
straighten me out. Any help?