E=hf...whats the units?Watch
E = Energy of the photon in Joules (J)
h = Planck's Constant (6.63 x 10^-34 J s)
f = Frequency (Hz)
You remember the equation E = QV?
Well an electronvolt is the E when the charge is equal to an electron's charge and the potential difference is 1V. The charge of an electron is -1.6*10-19 C.