COMEDK20269 May 2026Morning ShiftPhysicsAtomic PhysicsActual
An atom has a single electron. Its ground state energy is -30 eV and its first excited state energy is -8 eV . The atom is bombarded with a stream of photons, each of energy 15 eV . Assuming the atom being in the ground state, which of the following statements is correct?
Options
- AAtom gets excited to the first excited state and later emit photons of 22 eV
- BAtom absorbs energy continuously until 22 eV is accumulated and then gets excited
- CAtom will not get excited, and the transmitted light will have the same frequency as the incident light
- DAtom will absorb the photon and re-emit a photon of lower energy
Correct answer
C. Atom will not get excited, and the transmitted light will have the same frequency as the incident light
Step-by-step solution
The energy of the atom in the ground state is E₁ = -30 eV . The energy of the atom in the first excited state is E₂ = -8 eV . The minimum energy required to excite the atom from the ground state to the first excited state is E = E₂ - E₁ = -8 eV - (-30 eV) = 22 eV . The energy of the incident photon is 15 eV . For an atom to absorb a photon, the photon's energy must exactly match the energy difference between two states of the atom, or it must be greater than the ionization energy (which is 30 eV ). Since the incide