Question

If the differential amplifier gives a positive output then it infers which of the following (Reference output is given to the positive terminal and sample output is given to the negative terminal)?

(a) The concentration of silica in sample and reference solution is equal

(b) The concentration of silica in a reference solution is more than that in the sample solution

(c) The concentration of silica in sample solution is more than that in the reference solution

(d) Further processing is required to come to any conclusion

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This interesting question is from Silica Analyser topic in chapter Dissolved Component Analysers of Analytical Instrumentation

Answer 1

Right option is (c) The concentration of silica in sample solution is more than that in the reference solution

Easy explanation: If the differential amplifier gives a positive output then, it means that the concentration of silica in sample solution is more than that in the reference solution. It means that the photodetectors’ output is not equal.