When electromagnetic radiation of wavelength 2000 nm is incident on a metal surface, the maximum kinetic energy of the electrons released is found to be 4.0 × 10⁻²⁰ J.
Calculate the work function of the metal in joules (J).

You will need these values to answer questions:
Speed of light in a vacuum c = 3.00 × 108 m s⁻¹
Planck constant h = 6.63 × 10⁻³⁴ J s
Mass of electron m_e = 9.11 × 10⁻³¹ kg
Elementary charge e = 1.60 × 10⁻¹⁹ C