Question

The IR detector which consists of a small metal cylinder closed by a blackened metal plate on one end and a flexible metalized diaphragm on the other is

• A. Bolometer
• B. Thermistor
• C. Golay cell
• D. Pyroelectric detectors

Hint:

Golay cells are used to measure infrared radiation by detecting the expansion and contraction of a diaphragm caused by changes in temperature due to absorbed IR radiation.

Answer 1

The Correct Option is C

Step 1: Understanding IR detectors.
Infrared (IR) detectors are devices used to measure infrared radiation. They typically use a change in physical properties like resistance or thermal expansion to detect IR radiation.
Step 2: Analyzing the options.

• (A) Bolometer: Incorrect. A bolometer is an IR detector that measures the temperature change caused by absorbed infrared radiation, but it does not have the specific design described in the question.
• (B) Thermistor: Incorrect. A thermistor is a type of resistor that changes its resistance with temperature, but it does not fit the description of the IR detector with the diaphragm and blackened metal plate.
• (C) Golay cell: Correct. The Golay cell consists of a small metal cylinder closed at one end with a blackened metal plate and a flexible diaphragm, making it the correct IR detector described in the question.
• (D) Pyroelectric detectors: Incorrect. Pyroelectric detectors measure the change in polarization of a material when exposed to infrared radiation, but they do not have the structure described in the question.

Step 3: Conclusion.
The Golay cell is the correct IR detector, as it matches the description given in the question. Final Answer:} Golay cell.