Question

Which of the following is not a detector?

• A. Bolometer
• B. Pyrometer
• C. Nernst glower
• D. Golay cell

Hint:

In a spectrophotometer, you have a Source $\rightarrow\lt strong\gt Sample\lt /strong\gt \rightarrow$ Detector. The Nernst Glower is at the very beginning of that chain, while the Bolometer or Golay Cell is at the end.

Answer 1

The Correct Option is C

In the context of instrumentation and spectroscopy, a "detector" is a device that senses a physical property (like infrared radiation) and converts it into an observable signal (like electricity). 1. Analyzing the Detectors:

• Bolometer: A highly sensitive

detector used for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance.

• Pyrometer: A type of remote-sensing thermometer (thermal

detector) used to measure the temperature of distant objects.

• Golay Cell: A pneumatic type of infrared

detector that uses the expansion of a gas in a small chamber to move a flexible mirror.

2. Analyzing the Nernst Glower: A Nernst glower is a device made of ceramic oxides (zirconia, yttria, and erbia) that is heated electrically to high temperatures. When hot, it glows and emits a continuous spectrum of

Infrared Radiation.

3. Conclusion: Because the Nernst glower

creates/emits radiation rather than sensing it, it is classified as a

Source (specifically an IR source), not a detector. All other options are devices meant to receive and measure radiation.