The work function has the formula
E = h v
where
E is the energy
h is the constant
v is the frequency
Since the given is wavelength, we use the relationship between frequency and wavelength
v = c / λ
where
c is the speed of light
λ is the wavelength
So.
E = h c / λ
h = Eλ / c = 1.25 eV (475x10-9m) / (3x10^8 m/s)
h = 1.9792 x 10^-15
The work function is:
E = 1.9792 x 10-15 v
