Calculate the work function that requires a 475 nm photon to eject an electron of 1.25 eV.

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 = E λ / 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