Question

Which of the following is not the characteristics of Indium arsenide photovoltaic detector used in infrared analyzers for hydrocarbons?

(a) It operates at ambient temperature

(b) Has maximum detectivity at 3.4µm

(c) Sensitivity increases at longer wavelength

(d) It has no response to radiation of wavelength greater than 4µm

This question was posed to me in final exam.

Origin of the question is Infrared Gas Analysers topic in section Industrial Gas Analysers of Analytical Instrumentation

Answer 1

Right choice is (c) Sensitivity increases at longer wavelength

The explanation: The sensitivity of Indium arsenide photovoltaic detector decreases at longer wavelength. It is insensitive to radiation having a wavelength greater than 4µm.