Quantum Phenomena - discrete energy levels for electrons

Q2. Some energy levels of an atom of a gas are shown in diagram 1.

Diagram 1

When a current is passed through the gas at low pressure, a line spectrum is produced. Two of these lines, which correspond to transitions from levels B and C respectively to the ground state, are shown in diagram 2.

Diagram 2

(a) Describe what happens to an electron in an atom in the ground state in order for the atom to emit light of wavelength 4.0 × 10–7 m.

(3 marks)

(b) Determine the energy, in J, of

(i) the photons responsible for each of the two lines shown in diagram 2.

(ii) the enery of each of levels B and C in Figure 1.

(5 marks)

(Total 8 marks)