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JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Photon and Photoelectric Effect

  • question_answer
    The threshold wavelength for photoelectric emission from a material is 5200 Å.  Photo-electrons will be emitted when this material is illuminated with monochromatic radiation from a               [IIT JEE 1982; MP PMT 1992; MP PET 1999; UPSEAT 2001; KCET 2004; J & K CET 2004; BHU 2004]

    A)            50 watt infrared lamp

    B)            1 watt infrared lamp

    C)            50 watt ultraviolet lamp

    D)            1 watt ultraviolet lamp

    E) (e)     Both (c) and (d)

    Correct Answer: E

    Solution :

    (e)     In this case, for photoelectric emission the wavelength of incident radiations must be less then                                                                                                       \[5200{\AA}\] . Wavelength of ultraviolet radiations is less then this value (5200 Å) but wavelength of infrared radiations is higher than this value.


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