A certain atom has an energy level 3.50 eV above the ground state. When excited to this state, it remains $4.0 \mu s,$ on the average, before emitting a photon and returning to the ground average, before emitting a photon and returning to the ground state. (a) What is the energy of the photon? What is its wavelength? (b) What is the smallest possible uncertainty in energy of the photon?