(a)[4]
Explain the appearance of these darker lines by referring to discrete electron energy levels.
(b)[5]
Use band theory to explain how the resistance of a light-dependent resistor (LDR) depends on light intensity.
Physics 9702 · AS & A Level · Energy levels in atoms and line spectra
Energy levels in atoms and line spectra — practice question
As shown in Fig. 10.1, white light travels through a cloud of cool gas at low pressure. After the gas has been crossed, its continuous spectrum is observed to have several darker lines.