Photons of energy 6.0eV incident on a metal, it is found that current flows from the metal

Question:

Photons of energy 6.0eV incident on a metal, it is found that current flows from the metal until a stopping potential of 4.0V is applied. If the wavelength of the incident photons is doubled, what is the maximum kinetic energy of the ejected electrons? What would happen if the wavelength of the incident photons was tripled?