question_answer 43)

  Three photo diodes D1, D2 and D3 are made of semiconductors having band gaps of 2.5 eV, 2 eV and 3 eV, respectively. Which ones will be able to detect light of wavelength 6000  ?

Answer:

                  Energy of the incident photon,                 The incident radiations can be detected by a photodiode if energy of incident radiation photon is greater than the band gap. This is true for D2 (= 2 eV). Therefore, only D2 will detect these radiations.