Question

Infrared radiation are detected by:
A: Spectrometer
B: Pyrometer
C: Nanometer
D: Photometer

Answer 1

Hint The radiation whose wavelength is slightly above visible wavelength is called Infrared wavelength. Thermal radiations are usually under infrared region. Most of the radiations emitted by the objects in room temperature is infrared in nature.

Complete Step by step solution The wavelength range of infrared radiation is . Infrared radiation is usually called heat radiation since thermal radiations fall under the infrared category.
Now we know that the Pyrometer is a device that works in the infrared region, it is used to measure the temperature of a body without being in contact with the body. But it cannot measure the whole infrared spectrum.
Photometer is a device which can measure electromagnetic radiations from infrared to ultraviolet. So, a photometer can be used to measure the whole infrared spectrum.
Hence, infrared radiations are detected by photometers.

Hence option (D) is correct
Infrared radiations are extensively used in the fields of science, medicine, military and many more. Spectrometers are used to study the spectrum of the radiating bodies. If the body produces mixed spectrum a spectrometer is used to get a clear idea of the radiation.

Note Most photometers make use of photodetectors, photoresistors or photomultipliers. Modern DSLR cameras have photometers built in, in order to get correct exposure to a picture. Spectrophotometry (which is the quantitative method to measure the reflection or transmission properties of a material as a function of wavelength) in infrared light is mainly used to study structure of substance, as given groups give absorption at defined wavelengths.