In a photoelectric effect experiment, unpolarized beam of light is incident on a metal surface. Power is given as 28.0mW; frequency of the beam is 7.4* 10^14Hz; and stopping potential Vs as 1.45V.

-I was able to find the wavelength of the beam of light as 405nm.(c/f)
-Energy in the photon as 3.06eV. (hf)
-Max speed of the electrons ejected as 7.1*10^5m/s. [sqrt(2K.E_max/mass)]
-Work function as 1.61eV. (E_photon - KE_max)

But I'm stuck now. I am also supposed to determine the maximum photocurrent that could be produced by the ejected electrons; but I don't have any formula that calculates the photocurrent and I could not derive any.

Could anyone help please?
Thanks.

If you divide the power by the energy of the photon, you should get the no of electrons emitted per sec as there is a one is to one photon- electron correspondence. Multiply the no of electrons per sec with the charge of the electron to get the max photo current which is when the stopping potential is made zero.
Be careful of units electron volts , watts etc.