JEE Main & Advanced Physics EM Waves JEE PYQ-Electro Magnetic Waves

  • question_answer
    Infrared radiations are detected by [AIEEE 2002]

    A) spectrometer

    B) pyrometer

    C) nanometer

    D) photometer

    Correct Answer: A

    Solution :

    [a] Spectrometer is an instrument which is used to obtain a pure spectrum of white light. It is used to determine the wavelength of different colours of white light (or wavelength of monochromatic light source) the refractive index of the material of the prism and the dispersive power of the material of the prism.
                Pyrometer is infrared sensitive devices, so these are used to detect infrared radiations.
                Nanometer is the small unit of distance and is not a device.
    Photometer is used to measure luminuous intensity, illuminance and other photometric quantities.


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