Is this a ratio?

 

I've always held with the idea that physicists use division as ratio; well, as a way of trying to explain to classes that it doesn't have to have a colun in the middle to be a ratio. But I found myself writing that resistance is the ratio of potential difference to current. Is this a ratio? A bit of chasing references on the Internet suggests that mathematicians would want a ratio to be unitless ie both quantities to be divided would have the same units as in the turns ratio for a transformer. That is not the case here. However there is support for the idea that it is a ratio at http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmlaw.html which encourages me that it is an acceptable usage in physics.