Answer:
2.30 eV
Explanation:
Some details of the problem are missing:
"Light of wavelength 540 nm is required to extract electrons from sodium. What is the work function of sodium?"
The equation that describes the photoelectric effect is
where:
is the energy of the incoming photon, with
is Planck constant
is the speed of light
is the work function of the material
K is the maximum kinetic energy of the emitted photoelectrons
The minimum energy needed by the photons to extract the photoelectrons is that for which the kinetic energy is zero, so
K = 0
Therefore we have
In this problem, we know that the wavelength of the incoming light is
Therefore, we can find the work function of sodium:
And converting into electronvolts,