calculate the energy of the light when an electron in a hydrogen moved from n=4→n=2

calculating the energy difference between these two levels

∆E = E₄ – E₂

E₄= E₀ /n²

but E₀  = -13.6 eV

 = -13.6/16

=-0.85 eV

E₂ = E₀ /n²

 = -13.6/4

 =-3.4

 the energy difference is

∆E = E₄ – E₂

=-0.85-(-0.34)

= 4.25 eV