Answer:
See explanation
Step-by-step explanation:
If the energy of the ground state E1 is known, then we need to measure the difference in energy between the energy levels E5 .and E1. We can obtain this by measuring the frequency or wavelength of a photon that is emitted when an electron moves from energy level E5 to E1.
From Bohr's model;
ΔE = E5 - E1
Hence;
E5 = ΔE + E1