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A metal surface is illuminated by a ligh...

A metal surface is illuminated by a light of given intensity and frequency to cause photoemission. If the intensity of illumination is reduced to one-fourth of its original value, then the maximum KE of emitted photoelectrons will become.

A

twice the original value

B

four times the original value

C

one fourth of the original value

D

unchanged

Text Solution

Verified by Experts

The correct Answer is:
D
The maxium kinetic energy of photoelectrons is given by `KE_(max) = h (v-v_(0))" "…..(i)`
Where h = Planck's constant
v = frequnecy of radiation .
and `v_(0) =` thereshold frequency.
It can be see from Eq. (i), that the maximun KE of emitted photoelectron is proportional to the frequency of radiation and is independent of the intensity of radiation, so it remains unchaged .
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Knowledge Check

  • A metal surface is illuminated by a light of given intensity and frequency to cause photoemission. If the intensity of illumination is reduced to one fourth of its original value, then the maximum kinetic energy of the emitted photoelectrons would be:

    A
    Unchanged
    B
    1/16th of original value
    C
    Twice the original value
    D
    Four times the original value

  • If the amplitude of sound is doubled and the frequency reduced to one -fourth ,the intensity will

    A
    increase by a factor of 2
    B
    decrease by a factor of 2
    C
    decrease by a factor 4
    D
    remain unchanged

  • Assertion: A photosensitive surface is illuminated by a monochromatic light of wavelength lambda and intensity I. The number of photoelectrons emitted per second is doubled when the intensity of light is doubled. However, the maximum speed of emitted electrons remains unchanged. Reason: The number of electrons emitted per second is directly proportional to the intensity of the incident light. The kinetic energy of the emitted photoelectrons is independent of the intensity of the light.

    A
    If both assertion and reason are correct and reason is a correct explanation of the assertion.
    B
    If both assertion and reason are correct but is not the correct explanation of assertion.
    C
    If assertion is correct but reason is incorrect.
    D
    If assertion is incorrect but reason is correct.

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