Yes, FARADS is a Scrabble word!

Letter values in Scrabble US: F 4, A 1, R 1, A 1, D 2, S 1.

Is it a valid word?

FARADS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the capacitance of a capacitor that has an equal and opposite charge of 1 coulomb on each plate and a voltage difference of 1 volt between the plates

Also: f.