The photon energy, in eV, for electromagnetic waves of wavelength 40 m is

3.1 × 10−8 4.8 × 10−27 6.2 × 10−8 9.6 × 10−27

3.1 × 10−8

E = $h c / \lambda=\frac{6.63 \times 10^{-34} \times 3 \times 10^8}{40 \times e}$ = 3.1 × 10−8 ev